DISABLE_WAYLAND stops the Wayland socket from being created where it’s expected.
However, I don’t remember fully - but expect that DISABLE_WAYLAND doesn’t modify the $WAYLAND_DISPLAY variable itself at all, so your app will assume that there’s a socket to connect to and try do so, until it fails because the socket wasn’t created by the wrapper and the app falls back to X11.
Likely , you’d be better off having e.g.,
environment:
WAYLAND_DISPLAY: unset
This will encourage your app to not attempt to connect to Wayland in the first place, rather than deny it and force a fallback should it try.
Otherwise the errors just noise really.