Down graded to Monterey for stability, but far from stabel, what 2 do

So I Have tried all OSes except the most recent one on my Imac 27 Late 2009, but have had issues with mouse flickering when opening sub menues and such, the whole menue flickers i guess when hovering my mouse over them. So i thought ok lets go to the oldest version that makes sense and that was monterey, but I have had nothing but issues, the menue flickering still exists, but now my graphics get all wierd, like my screensaver and open windows turn into scrambled eggs and it moves slowly to left and then the screen is ok again, just for it to happen again and again. And the Imac keps freezing now and then. Non of these issues where present when i ran Ventura or higher. Not sure what im missing here, but I thought the lower the more stabel the OS would be.

Im now unsure if I should upgrade to ventura again or see if I find answers to my Monterey problems.

IS there a fix to the issue with flickering sub menues and right click and dropdowns in general ? ( to be more specific the menues/dropdowns flicker and highlighting files and such becomes difficult, instead of highlighting they might Open or do other things instead what your intention is, livable but very annoying.