Maybe screen curtain is active, have you tried to disable it?
'''"Use Screen Curtain on your Apple Watch'''
Use your iPhone to turn on Screen Curtain for your Apple Watch:
# On your iPhone, open the Apple Watch app and go to My Watch.
# Tap Accessibility > VoiceOver > Screen Curtain. This setting keeps Screen Curtain active whenever VoiceOver is on.
# To turn Screen Curtain off, repeat these steps."
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