Effective March 31, 2024, Bulgaria and Romania are considered members of the Schengen area, but only by air. If you travel by car, train or bus, official passport controls will continue to take place.
As of March 31, 2024, the change for airline passengers will be that flights to/from Bulgaria and Romania will in future be handled in the Schengen areas of the airports. Police passport checks will then no longer be necessary. For the time being, this relief only applies to air transport, as official controls continue to be carried out over land. The Austrian federal government under Karl Nehammer (ÖVP) literally enforced this special regulation.
and 