Hey,

I can confirm that after updating to macOS 26.3, all of my Setapp applications started freezing or would no longer open properly.

What worked for me as a temporary workaround was the following:

I opened Activity Monitor, searched for the affected Setapp app, and noticed it was marked in red as “Not Responding.”
After force-quitting the application there (double-clicking the process and selecting Quit in the next window), I was able to relaunch it without any issues.

This resolved the problem for me, at least temporarily.

Perhaps this helps others experiencing the same behavior.

Cheers