Applications crashing after opening

Suggest downloading the Application Etrecheck directly from a well Respected ASC Contributor. 

Disclaimer: I am not affiliated with nor receive compensation from the Developer.

The application is free or paid from added features. 

Run the application with Full Disc Access ( Security & Privacy - Full Disc Access ).

It will take a Snap Shot -  both the hardware and software.

The Report will Not Reveal Any Personal Information. 

Post back the Full Report - copy and paste - using the Additional Text Icon ( 3rd Icon to last )

We can have a look at the report for possible issues and may have possible suggestions to resolve the issues.

Any Third Party Applications that will interfere with the normal operation of the OS, alter, modify, remove or delete or attempt to do so is an invitation for disaster and may require a Reinstallation of the OS.

This includes AntiVirus, Cleaners, Optimizes, UnInstaller etc.

The The Built in Security  is all that is required.

In addition to the clean up suggested by P. Phillips, have you completely uninstalled Rekordbox and rebooted, then tested for other apps crashing?

If the crashing problems go away after completely uninstalling Rekordbox, you then might review this link https://discussions.apple.com/thread/253306266 for relevance and to try when you reinstall Rekordbox. It includes some workarounds for Rekordbox incompatibility with the latest Catalina Security Update, which I see you have installed.

Based on the age of your Mac, you might consider booting into Recovery and running Disk Utility First Aid to check the disk file system and also use DriveDx to check its physical condition. You may also need a new battery but I don't see how that would cause apps to be crashing.

I suggest that you review these two discussions as it appears that others with the HD 4000 Intel graphics (which I think your computer has) are reporting issues after that Security update:

After Security Update 2021-007 for Catalina, Google Earth Pro isn't working anymore

After security update 2021-007 for catalina MAMP isn't working, Graphics kernel error: 0xfffffffb

However, it has also been reported that in Safe Mode the issues went away. Have you tried Safe Mode? Safe Mode disables third party extensions. If Safe Mode works ok for you, then that is a clue about what might be going on.

My 2013 Macbook Air works fine with all the updates applied but it has the Intel HD5000 graphic, not the HD4000.

Unsigned files - There are unsigned software files installed that could be adware and should be reviewed.

Adobe Flash Player installed - Adobe Flash Player is installed on this computer. This is a security risk and no longer supported.

Security Risk! - Adobe Flash Player installed!

High battery cycle count - Your battery may be losing capacity.

Battery: Health = Normal - Cycle count = 785

Clean up - There are orphan files that could be removed.

System modifications - There are a large number of system modifications running in the background.

Kernel extensions present - This computer has kernel extensions that may not work in the future.

Unsigned Files:

Launchd: /Library/LaunchDaemons/com.adobe.SwitchBoard.plist

Executable: /Library/Application Support/Adobe/SwitchBoard/SwitchBoard.app/Contents/MacOS/launch.switchboard

Details: Exact match found in the legitimate list - probably OK

Launchd: ~/Library/LaunchAgents/com.citrixonline.GoToMeeting.G2MUpdate.plist

Executable: ~/Library/Application Support/CitrixOnline/GoToMeeting/G2MUpdate

Details: Exact match found in the legitimate list - probably OK

Launchd: /Library/Apple/System/Library/LaunchAgents/com.apple.MRTa.plist

Executable: /Library/Apple/System/Library/CoreServices/MRT.app/Contents/MacOS/MRT -a

Launchd: /Library/LaunchDaemons/com.rane.sixtytwo.daemon.plist

Executable: /Library/PrivilegedHelperTools/SixtyTwoSettingsService

Details: Exact match found in the legitimate list - probably OK

Launchd: /Library/LaunchDaemons/com.microsoft.office.licensing.helper.plist

Executable: /Library/PrivilegedHelperTools/com.microsoft.office.licensing.helper

Details: Exact match found in the legitimate list - probably OK

Launchd: /Library/LaunchDaemons/com.rane.sl3.daemon.plist

Executable: /Library/PrivilegedHelperTools/Sl3SettingsService

Details: Exact match found in the legitimate list - probably OK

Launchd: /Library/LaunchDaemons/com.adobe.fpsaud.plist

Executable: /Library/Application Support/Adobe/Flash Player Install Manager/fpsaud

Details: Exact match found in the legitimate list - probably OK

Launchd: /Library/LaunchDaemons/com.rane.sl4.daemon.plist

Executable: /Library/PrivilegedHelperTools/SL4SettingsService

Details: Exact match found in the legitimate list - probably OK

Launchd: /Library/LaunchDaemons/com.rane.sixtyone.daemon.plist

Executable: /Library/PrivilegedHelperTools/SixtyOneSettingsService

Details: Exact match found in the legitimate list - probably OK

Launchd: /Library/LaunchDaemons/com.rane.sl2.daemon.plist

Executable: /Library/PrivilegedHelperTools/SL2SettingsService

Details: Exact match found in the legitimate list - probably OK

Launchd: /Library/LaunchAgents/com.divx.update.agent.plist

Executable: /Library/Application Support/DivX/DivXUpdate.app/Contents/MacOS/DivXUpdate /silent

Details: Exact match found in the legitimate list - probably OK

Launchd: /Library/LaunchAgents/com.divx.dms.agent.plist

Executable: /Library/Application Support/DivX/DivXMediaServer.app/Contents/MacOS/DivXMediaServer

Details: Exact match found in the legitimate list - probably OK

Launchd: /Library/LaunchDaemons/com.microsoft.OneDriveUpdaterDaemon.plist

Executable: /Applications/OneDrive.app/Contents/OneDriveUpdaterDaemon.xpc/Contents/MacOS/OneDriveUpdaterDaemon

Details: Exact match found in the legitimate list - probably OK

Launchd: /Library/LaunchDaemons/com.rane.sixtyeight.daemon.plist

Executable: /Library/PrivilegedHelperTools/SixtyEightSettingsService

Details: Exact match found in the legitimate list - probably OK

Login Item: ~/Library/Application Support/Google/Android File Transfer/Android File Transfer Agent.app

Login Item: /etc/mach_init_per_user.d/com.adobe.SwitchBoard.monitor.plist

Plugin: /Library/Internet Plug-Ins/Flash Player.plugin/Contents/PlugIns/FlashPlayer-10.6.plugin

Plugin: /Library/Internet Plug-Ins/DivX Web Player.plugin

Plugin: /Library/Internet Plug-Ins/Flash Player.plugin

Plugin: /Library/Internet Plug-Ins/OVSHelper.plugin

Plugin: /Library/Internet Plug-Ins/SharePointBrowserPlugin.plugin

Plugin: ~/Library/Internet Plug-Ins/WebEx64.plugin

Plugin: ~/Library/Internet Plug-Ins/CitrixOnlineWebDeploymentPlugin.plugin

Plugin: /Library/Audio/Plug-Ins/HAL/SeratoVirtualAudioPlugIn.plugin

Preference Pane: /Library/PreferencePanes/Flash Player.prefPane

Preference Pane: /Library/PreferencePanes/SIXTY-EIGHT Audio Control Panel.prefPane

Preference Pane: /Library/PreferencePanes/Sixty-One Audio Control Panel.prefPane

Preference Pane: /Library/PreferencePanes/Sixty-Two Audio Control Panel.prefPane

Preference Pane: /Library/PreferencePanes/SL 2 Audio Control Panel.prefPane

Preference Pane: /Library/PreferencePanes/SL 3 Audio Control Panel.prefPane

Preference Pane: /Library/PreferencePanes/SL 4 Audio Control Panel.prefPane

Good work there :-)