This seems to happen with almost any airplane at any airport to some extent. I don’t do any of the addon airliners and I don’t have many addon airports and none of the large ones, but the effect is almost always there.
I’ve sort of been watching this behaviour and what I’ve noticed is that at some point on the approach, there will be a spike the the data being downloaded followed either by a stutter or a drop in FR or both. It seems like the sim suddenly decides it needs all the airport-related data, downloads it and tries to render it in one “gulp”. Once that’s done, the diminished FR reflects the fact the sim is now preparing to display all the “airport stuff”…runway environment, vehicles, suicidal ground crew etc…
My observations for now.