Some games hog the mouse input when two apps are open simultaneously

[Managor]

Your system information

• Steam client version (build number or date): 1710281934
• Distribution: SteamOS
• Opted into Steam client beta?: Yes
• Have you checked for system updates?: Yes
• GPU: AMD

Please describe your issue in as much detail as possible:

Demonstrative video: https://youtu.be/dPuvd1Pbiq4 Some games hog the mouse input from other apps that are open alongside them in gamemode. It doesn't seem to make a difference if the other app is Steam or non-Steam. There doesn't seem to be any outward commonality with the games I've tested and only very few games have this behavior.

If I simultaneously open two games that hog the mouse, like Digimon World: Next Order and Outer Wilds, both of them receive the input

I have also been informed that this can also be reproduced with Fallout New Vegas+Nexus Mod Manager and Persona 5+FlawlessWidescreen. I am unable to test myself.

The games I've identified are: Digimon World: Next Order Outer Wilds Bioshock Remastered Cave Story+ Deus Ex: Game of the Year Edition Insaniquarium Mafia

Reproduction steps:

1. Open one of the listed games
2. Launch something like discord as a second program
3. Open the second program
4. Attempt to click on anything on the second program

Expected results:

The second program should get mouse input

What actually happens:

The second program doesn't get any mouse input from the pointer or buttons

Additional info:

I've reported this previously in the steam forums https://steamcommunity.com/app/1675200/discussions/1/4039230033356627826/