Titanium barrels are meant to be superior to normal barrels in rocket capacity, but some fluids (like atmosphere for Maraxsis) has a larger barrel capacity, so packing these with titanium barrels will actually result in less fluid per rocket. Could you implement a dynamic barrel capacity, copying the size of normal barrels instead of using a hard-coded 50?

none of fluids should have wierd capacity (in relation to all barrels at the same type) in first place

And I just double checked that
with just pelagos and maraxsis installed both barrel take 50 units of fluid

you have some other mod messing with it and causing this inequality to happen

all barrels of the same type should have same capacity

Okay after a second look in game, it's not Maraxsis but Muluna which make some gases (H2, O2, CO2, plus atmosphere) to have 500 barrel capacity. It's not a neccesity but I think it'll look nicer if you could implement something for this.

I am not supporting muluna