Is solder mask necessary?

[lardom]

@Piotr

No. Your conclusion goes too far.
You only know that a problem can be solved by replacing motors with LEDs
I suppose solving the problem would need some schematic changes and not only PCB design changes.

I hope the forum will allow me to ask for advice concerning schematic changes if the need arises.
The LED tests will also help me see if my code is a problem.