New keyboard pushing extra buttons in steam

[Jon.Topps]

Other applications like Chrome and Word and PowerPoint don't have this issue, but when I'm in Steam overlay (specifically the overlay function), it repeats button presses a lot. So insteeeeead of oooooone butttttton it will do stuff like that.
It's a new mechanical keyboard, my previous one wasn't (the key works when only half pressed).

Is there like a setting or something I can change to fix this? Either in Steam, or Windows?
Thanks!