I installed 9.3.7 on a fresh install of Trixie on my old pi3 and it works fine. It’s using Wayland (labwc) – I selected Wayland in raspi-config and rebooted. Every time I connect from my Win 11 PC I get a window with a white screen for 2 or 3 seconds, then the normal pi desktop. No idea why the Pi5 is having troubles with the same OS. They’re both plugged into the same TV via HDMI.
It turns out logging into a browser every time is a nuisance (for Connect) and I much prefer using NoMachine. Might have to switch to x11 on the Pi5 temporarily.