Sudden issue with acceleration (w/gamepad)

[TheClubber]

Hi everybody.
It’s almost a year I play ETS2 on an iMac 24”.
Until few weeks ago I used an original PS4 gamepad then I sold the ps4 and bought a new gamepad which is compatible (indeed Steam recognizes it as a PS4 controller).
The problem is that, sometimes, the acceleration button (L1 in my case) doesn’t work properly, no matter how much I push it, it seems the truck has some kind of speed limitation.
If I push the keyboard key (“W” as default settings) the truck accelerates correctly.
To restore the function I need to unplug and plug again the pad.
I also noticed that if I’m going backward and I push L1 to go forward it struggles to change gear from reverse to drive.

What can it be? It really seems some kind of bug in the controller settings.

[TheClubber]

I want to update the issue: I tried to switch two buttons (L1 for lights and L2 for throttle). it worked for a while then the issue came back. Practically, the L1 now works fine while L2 doesn't. Once again the only way to fix it is to unplug and plug the controller.