How do base SL multipliers work?

Today I noticed that planes in my “main” tree, Germany, have a much higher SL multiplier than similar vehicles in every other nation.

For example, my MIG 29 has a base of 3.2:

Whereas the MIG 29 in the USSR tree has a base of 0.9:

I can only assume that the increase has something to do with my progress in the German trees but I can’t figure out what.

Trying again for the images.

Look at the very bottom, you will see that the ussr one says “information relevant to arcade battles”, and the German one says “information relevant to realistic battles” this is because you get more SL per useful action (like kills, bases bombed, AI targets destroyed) in realistic battles than in arcade. You can select which gamemode’s info that stat card shows in the research/tech tree.