This is my fix routine when something is quirky and unexplained (you can actually get incompatible OS files from time to time, and sometimes you download some software that is, ummmmm, suspect, so:I bought a MacBookPro16,1 last year(?), and it's been a rather disappointing thing in my life. Lagging, stalling, and downright seizures. Typing along, and the system is still on the word I typed over a minute ago. I haven't opened a case because others inflicted with the same diseases say all Apple does is want to swap it, and/or then deny there is a problem. It was an unexpected purchase due to me waiting until my butterfly keyboard got 'bad enough', and was outside their generous repair/replacement time. It generally works well, but goes through fits of obstinate behavior and sullen mood... Not impressed, disappointed actually, but at least the keyboard works. Small victory there... It does *seem* better with the new update, but I haven't been using it as much either.
1) reset SMC, VRAM, PRAM. all you've got
2) backup - with iCloud, google and one drive this is easy.
3) clean install
I am on developer beta so I am updating with betas a lot, I do this with every major update. Last time I did not, I got a publicized safari quitting problem. the procedure above fixed it straightaway.