I recently started playing sf6 in online mode.
Playing against other pc users seems to work just fine,
however Crossplay matches fail with the error code 50200-21018 (as far as i understand the first digits designate the http status code 502)

I talked to a steamdeck user for which crossplay worked just fine I play on silverblue using the flatpack version of steam.

At first is Suspected problems with the proton version,
and tried several diffrent versions (including GE) However this did not help.

Updating my ostree and flatpacks did also not help.

does anyone have suggestions on what might be causing these issues, or how to debug it further?

EDIT: same error occured when i tried using the steam version from the os