hmmm, I loaded the zone again and once more the roundabout has double sections, one having the turn restrictions, the other uncut circle the flixbus relations. Also no idea why you started editing other stuff outside your route. Was not asked for. Just apply your route to the roads as is, not more not less. No objections to cut up roundabouts to avoid these silly full loops which the drivers obviously don't do either, they take the shortest way on-off.

v.v "also make the roundabout as one way", roundabouts when drawn in the proper direction don't need to be oneway tagged unless you meant the roundabout as a single line way. That of course can't be with the turn restrictions.
Anyway double ways is no go and has me concerned this is not happened elsewhere as well with whatever tools you use to fix Flixbus routes.

I use JOSM and I know it can, but avoid any mucking with their route order. Doesn't matter where one touches a road with a Flixbus link and PT reports problems by the bushel, no different today over at Peligna Pratola where a roundabout was incorrectly mapped with shortcuts. Sure enough this odd full looping is wholly unnecessary.

ciao