The drone should have a fix repair-lvl of 30 HP, right? Plus max. 5 Hp for max. fusion, right?

Well, my drone does what it wants...

It has fusion level 3, so the healing every round should be 33, right?

Would be nice. My drone repairs what it wants. 33 is max. But I just had a match where it repaired just 1 HP three turns in a row!!!

11HP, 22, HP, 1 HP, 33 HP ... what it wants...

I believe liran changed the drone such that it can only repair 1 more HP than the amount of damage your mech received that turn capping off at 30-35 (depending on fusion.)

so if you did not take damage that turn you will only heal 1 hp (0dmg +1)