Don't know if this is related, but I thought I'd test on the demo version of my game that I just updated. ALT+TAB away and back and keyboard input only works if I click inside the window. I didn't try a controller. But I closed the demo and it crashed and brought Steam down with it. I couldn't restart Steam but after some back and forwards with ChatGPT, I got it running again but then replicated the same issue again. (Windows 11).
I did remember that I'd forgotten to apply the fix described here to get Xbox controllers working (at the expense of the Steam overlay):
construct.net/en/forum/construct-3/general-discussion-7/xbox-controller-not-working-187241
Not sure if that's related.
The full version (using a different Steam account on a Windows 10 laptop) appears to be working fine.
I need to do some more troubleshooting...