Not that it's much use, but I can confirm that the RPi 4 running Buster works with VNC just fine - I'm using mine in headless mode without any issues at all. Might be worth you flashing your SD card with a clean installation of Buster, setting the SD card up with SSH enabled and wifi already set up ...

AIUI, running the vncserver from the command-line via SSH invokes the virtual mode server - hence the :1 . Although you say you enabled the ("normal") service via the raspi-config GUI did you also enable boot to desktop (rather than command-line)? (Possibly a "red-herring") Trev. Ah, thanks - runni...

I'm no expert with Linux, but I managed to get VNCServer running just fine on my RPi 3 B+ so that I could use it in headless mode and, when it was rebooted, VNCServer would start with no problems and I could connect to the Pi's Raspbian desktop from VNC Viewer in Windows 10 with no issues whatsoever...