I've seen tons of other bugs related to MBP+external monitor over the years, with multiple MBP / OS versions.
My current issue is that I use an ultrawide curved monitor at work, and when I lock the screen and then unlock it, some of my previous window positions are changed on the external monitor. My large-but-not-fullscreened IDE that takes up ~85% of the external monitor is resized and shifted off screen, every time. I have to use the 4-finger swipe up gesture to see all windows, drag the now-visible IDE window into a new desktop panel at the very top, then minimize it from fullscreen, to get back to where I was before I pressed ctrl+cmd+q...
My current issue is that I use an ultrawide curved monitor at work, and when I lock the screen and then unlock it, some of my previous window positions are changed on the external monitor. My large-but-not-fullscreened IDE that takes up ~85% of the external monitor is resized and shifted off screen, every time. I have to use the 4-finger swipe up gesture to see all windows, drag the now-visible IDE window into a new desktop panel at the very top, then minimize it from fullscreen, to get back to where I was before I pressed ctrl+cmd+q...