I have been seeing all of the above problems on my 16GB M1 MacBook Air for probably at least 6 months now.
WindowServer has consistently been the main culprit but occasionally other apps like to chip in where they can too. Often that means there isn’t one single process which I can kill to reclaim enough memory to continue working without being promoted again or having MacOS forcibly close all my applications on me. As a result, reboots appear to be the only real solution for me.
Interestingly though, in the past few weeks I have been working with similar numbers of open Sublime Text windows as yourself and I can confirm that since then, ST4 has been a regular and serious offender when it comes to memory usage in Activity Monitor.
WindowServer has consistently been the main culprit but occasionally other apps like to chip in where they can too. Often that means there isn’t one single process which I can kill to reclaim enough memory to continue working without being promoted again or having MacOS forcibly close all my applications on me. As a result, reboots appear to be the only real solution for me.
Interestingly though, in the past few weeks I have been working with similar numbers of open Sublime Text windows as yourself and I can confirm that since then, ST4 has been a regular and serious offender when it comes to memory usage in Activity Monitor.