Well, just logoff/login is enough to workaround this issue as X is restarted.
Just a small update: in this ten days or so I used FreeBSD as my daily driver and I have to say I'm really impressed, my personal workload is 99% unchanged. The only thing that doesn't work is iPhone backup and I had to fetch an old laptop (running W11 despite no TPM, no UEFI and no supported CPU
) just to run iTunes. No big deal.
For my GPU suspend/resume problem: I updated to 15-CURRENT (BTW, the procedure is so well documented that it was a breeze for me) but the problem persists unfortunately.