I’ve flown with them twice this year with the road bike and no problems.
Both times I’d packed a lot of other stuff in with it, helmet and shoes both times plus a lot of dirty clothes on the way home. Both times had CO2 canisters and at least once GT85 and lube.
Last time I used a hard case, with that, the bike and the extra gear in it weighed in at 27kg, other bag was over 5 but not much. No problems.
Only thing that really had me worried was carrying SIS energy powder in a water bottle, white powder hidden in a water bottle could very easily have caused a search but thankfully didn’t as it was pretty tight getting the case to shut with the wheels in there.