Reinstalling the Combo update macOS 10.15.4 https://support.apple.com/kb/DL2037?locale=en_US
on top of your existing macOS 10.15.4 is known to sort one off anomalies.
To trouble shoot further you can:
Try a SafeBoot https://support.apple.com/en-us/HT201262
Takes noticeable longer to get to the login screen, does a 5-15 minute disk repair before it fully boots up, and certain system caches get cleared and rebuilt, including dynamic loader cache, etc. Login and test. Reboot and test as caches get rebuilt.
This test will tell you if third party interference; extensions etc are not loaded in safe boot mode.
Test issue in another user (or guest user) account https://support.apple.com/en-us/HT204443
This will tell you if it a universal issue or isolated to your user/admin account.
if no progress or resolve—
To get a good look at your System config. for conflicts or issues, you can download/run this trusted utility https://etrecheck.com
If you need help interpreting the report you can post it here in its entirety in the "Additional Text" box in the editing toolbar below, in your reply.

You can set its preference to "Allow full Disk Access", with this you get a digest of issues from the last 7 days that are saved in your system. _No_ personal information is revealed.
