Did you do a big system upgrade recently and notice you're having gamepad issues? You're not alone. Time to downgrade perhaps.
To be clear this might only be an issue for the more bleeding-edge distributions which update more often, or those of you who are doing some manual updates to their system. The distributions that update more slowly like Ubuntu are likely unaffected right now.
First we have systemd version 243 released around September 3rd, this appears to be causing problems with Steam Input. A Valve developer jumped into the comments there, to note that the update seems to have broken Steam's udev rules to support gamepads—ouch. The systemd developers have been responsive trying to fix it, so hopefully it won't be too long before the issue is solved there.
Another problem is the more recent release of the Linux Kernel 5.3, which appears to have a regression with the DualShock 4 over Bluetooth not working. As of yet, no Kernel developer has commented on that report.
Hat tip to Vash63.