Please note that there is a known problem under MacOS 11 and later: the close button no longer works on some graphics apps, though it continues to work on others. It is unclear why.
Since the graphics apps are provided by the projects, we have no way to fix this at our end. Our solution (really a workaround) was to modify the BOINC Manager so the "Show Graphics" button changes to "Stop Graphics" when the graphics app is displayed.
> Dear Mac alpha testers,
>
> I have built a new hot fix release for the Macintosh only, BOINC 7.20.4.
>
> The only changes from the previous 7.20.2 release should be to fix the "Show Graphics" functionality in BOINC Manager and to the screensaver under MacOS 13 Ventura. Please download and try <
https://boinc.berkeley.edu/dl/boinc_7.20.4_macOSX_universal.zip> and let us know if you find any problems.