The group of friends I play with have been having this issue since SU7.
Planes that came with the game most of the time show up in our group as a single engine prop plane. Though I have to admit, today we were in a group and were using the TBM30 and it actually showed all of us in the TBM30.
I feel your pain on this one as when I am flying around solo, or with the two other friends that I play with, we get buzzed by a F22 that shows up as a single engine underwing prop plane, even though we all own the F22. It is super annoying and really takes the reality/fun out of the sim.
I really hope someday we will be able to see the planes whether we own them or not, and they need to fix whatever the issue is of us not being able to see planes that came with the game! I would go on with more details but I do not have the time right now. If anyone has a fix, I would LOVE to hear it.
Just to clarify, we are all on Xbox Series X.