Very dim RGB LED strip when using MOSFET
The threshold voltage of the FET you linked is typically 3V, and can get up to 4V:



Which means that with the ESP32s GPIO you are not guaranteed to fully turn them on.

Try connecting the gate of a FET to 5V and see if the strips light up correctly (disconnect the ESP32s GPIO first).

If that solves the problem then you have 2 options:

1 - get a FET that is guaranteed to fully turn on at 3.3V (try looking for a Threshold voltage of around 2V)

2 - use something to drive the FETs gate to a proper voltage. A level shifter or a discrete transistor setup to drive the FETs gate, for example.

If that doesn't solve the problem, then the issue is something else.

p.s.: GND is not -12V