Im trying to use Medibang cause sai is getting on my nerves ...

BUT this always happen with ANY pencil i use
it's like it looses the pressure or smt ? just suddenly
and i don't know how to fix it , i mean compare the doodle i did seconds
before that happen , the other lines have no pressure at all
it looks like an error cause in other drawing programs the pressure of my tablet
works just perfectly .