Has the signage changed here when you surveyed it recently? The previous most recent survey (https://www.openstreetmap.org/changeset/133637602) noted that the signage says ‘cyclists dismount’. So even if it’s incorrectly using that in combination with a no cycling sign, that would suggest the correct tagging *is* bicycle=dismount.

Changing this to bicycle=no is quite a drastic move, given that this way is part of NCN6.