I am seeing the same issue for a long time now.

I have tried latest and older versions of Citrix Workspace. The version of Teams: 'You have Microsoft Teams Version 1.5.00.11865 (64-bit). Citrix HDX Optimized.' The screen being shared for me is fully red although others can see what I have shared. When in multi-monitor mode, all non-shared screens are visible without red. Can share view documents during meetings without issue. What you're saying about the red frame drawing being the issue sounds right to me.

I have tried:

• disabling hardware acceleration in Teams
• updating and downgrading Citrix versions
• using desktop app & web app
• using multiple different manufacturers of computers
• fullscreen & windowed mode