I'm experiencing an issue using last version Rstudio, both on Mac and Windows.
Sometimes appears a little square (on Mac) or semi-rounded on Windows. I think the trigger is the cursor movement, sometimes appears and most of the times disappear if I click on it.
It remains in the same position if I scroll the script.
On Mac I downgraded 3 weeks ago on 2022.02.3 and the problem disappeared.
R and Rstudio are just installed on my windows machine, after a clean install of the OS, so can't be a coincidence.