Make sure your Silverlight and Java plugins are up to date. You may as well uninstall the Adobe Flash plugins since they will no longer be supported after the end of the year.
You really don't need to have MalwareBytes running all the time. You can turn off the real-time scanning and just manually run it periodically. Maybe it is interfering.
Make sure to keep at least 20GB of free storage space available on the laptop's SSD. If you go below that system performance can suffer which could also affect your network connections.
During this boot when the EtreCheck report was run you had 1.3GB of Swap being used on the SSD which means the memory contents were offloaded to the SSD. While this is normal, it can also slow down the system a bit depending on whether this occurred all at once or just little bits over time.
The SSD's write speed seems a little bit on the slow side, but not by much as most reports show the write speed around half the read speed. The slower write speed during the EtreCheck report may have been due having written a lot of data shortly before running EtreCheck.
Try running Disk Utility First Aid on the SSD. Even if First Aid reports everything as "Ok" click on the "Show Details" and look through the report to see if there were any unfixed errors listed.
Try creating a new user account. Then log into the new user account to see how it performs. If a new user account works, then you likely have a preference issue with the main account.
Try clearing the cookies and cache files from your browsers. You should be able to do this through the browser's privacy settings.
You can also try booting into Safe Mode to see if there is any difference. Safe Mode disables a lot of startup & login items plus it deletes some temp and cache files.
You may want to try reinstalling Catalina overtop of itself.
You should check to see whether your laptop qualifies for the free Apple SSD repair program:
https://support.apple.com/13-inch-macbook-pro-solid-state-drive-service
FYI, here is the current list of all the publicly acknowledged free repair programs for various Apple products. Some products such as your laptop have multiple programs):
https://support.apple.com/service-programs
