Instead of default model (Woman in White Clothes) it replace with a special ghost character like those seen in Little Crusaders.
If the game notices the Workshop model has been blocked for whatever reason such as turning off Workshop altogether or just blocked.
Heck, make it a ghost cat to stay close to the theme of Tower Unite.
the thing is you technically have an in-game playermodel chosen even if you’re currently using a workshop one - and that in-game playermodel isn’t just about saved choice for woman/man/skeleton/milk but also all the colors you set up for it.
The issue is that, I believe, this is what blocked workshop models are supposed to fallback to - but they don’t, instead displaying default model with default white colors.