For a Level 1 it takes this long to level up. Not to mention the first variant of the Flamethrower is much weaker than those of Normandy in later Levels. Just for a Level 3 Flamethrower its already cost this much XP to level and its a massive pain to level them up
Screenshots ends up too blurry. But for a Level 3 Flamethrower i need 14130 XP to level up. Which is an insane amount for the very first variant, its as if you are levelling the M2 Flamethrower squad
M2 Flamethrower squad takes 20570 XP to level up on Level 3 so its the same. But the Flamethrower on Berlin is so much weaker and they should really be on Tier 2
Both ROKS-2 and Flammenwerfer 35 are bad, take way too long to kill and have short range.
Btw, most caps in berlin are on open ground or inside large spaces. Only few caps are inside confined spaces (like Goebbel’s Villa on Ministry Garden or Hitla’s office on several maps) where Flamethrower can be most effective.
I personally just skip those squads and send all but the first flametrooper to the rear.
It should be similar to the progression of the Moscow flame squad. This squad is one of the hardest to level up other than fighters cause T1 flamers stink.
Just don’t bother playing as one of the flamers unless you are defending a room and it will be easier.
You need to play the early flamethrower squads as ordinary infantry rather than relying on the FT - use it when it is useful - but that’s not very often.