I had been been running Catalina and MATLAB 2019B without too many problems for a while (make sure you’re on 2019B–earlier MATLAB versions are not compatible with Catalina, at least not nominally/you take your life into your hands if you do). I did have a problem after installing the most recent update 5 for 2019B that PTB’s KbCheck stopped being able to take input from the keyboard. I was able to fix it by quitting MATLAB, going into Mac System Preferences → Security & Privacy → Input Monitoring and unchecking MATLAB, restarting MATLAB, quitting MATLAB again, and re-checking MATLAB in Input Monitoring. Not sure if every quit/restart of MATLAB in that sequence is strictly necessary–these are just the exact steps that worked for me. Basically it looks like either MATLAB or the Mac had forgotten that I had granted keyboard access to MATLAB in the past, so I just re-did it. KbCheck working normally now.
I know MATLAB have had some hiccups adjusting to Catalina–things like MATLAB hanging on startup, that kind of thing. Each MATLAB update gets a little better.
I tend to trust Apple’s judgment calls when it comes to security measures given that I’ve never needed to worry about viruses and such. Personally I also like the feeling that nothing can use my laptop’s camera unless I’ve explicitly clicked to say it can. I don’t know much (anything) about the technical details, of course–I just know that I’ve never had a security-related issue under Apple, and that feels like a good track record to me.