I run into bugs every day. It wakes, and has a black screen not wallpaper. Change spaces and the focus is wrong for half a second. Login screen is a pain because it collapses all users together. Notifications don’t scroll if they stop scrolling when the cursor is over a gap between them. Something on the system constantly eats disk space, and I think it’s the system updates. If I dock two apps in one space, sometimes one is black. If I zoom out to the Spaces overview it shows fine in the preview though. In the Terminal if I close a tab it can focus an entirely different window.

I could go on for hours. It’s a buggy mess these days and I miss Lion and Snow Leopard desperately.

Unless these problems only started after an upgrade to Tahoe, I would strongly suspect defective hardware in your case.