I have an ipad pro 10.5 with 256GB. Airports I tested and experienced low frame rate were San Diego, Palm Springs and SFO. But in another thread this was already picked up by you.
I noticed some new objects in Palm Springs and wondered whether this causes the choppy experience.
Prefer the previous experience.
Edit: SFO in R22 - unplayable. Flight school crashes App immediately.
BTW: Again, I had to go to the app store, look for the FS2019 App and then click on the update button. The update was not announced on my ipad as usual.