Is the plan for Bulgaria to join the Schengen Area related to the war in Ukraine? No, that's not true: The European Union member state is legally obligated to join the Schengen Area when it meets agreed requirements, regardless of its policy towards Ukraine.
The claim appeared in a TikTok video (archived here) on May 16, 2023, the day that the European Commission unveiled a State of Schengen report for 2023, in which it reiterated its support for the accession of Bulgaria and Romania to the area. The narrator says (as translated):
Suddenly they rushed to accept us in Schengen. 100 years of delay, and now all of a sudden. Guess why? They want to bring us into the war in Ukraine. If we are not in Schengen, we will separate from Europe. Go die alone in the US wars.
This is what the post looked like on TikTok at the time of writing:
(Source: TikTok screenshot taken on Thu May 18 20:04:11 2023 UTC)
No official European or Bulgarian commentary has linked Bulgaria's Schengen candidacy with its policies toward the war in Ukraine, and the European Commission insists that Bulgaria will join the border-free Schengen zone once the country meets the requirements for membership. It is both a legal expectation and a European promise that the 27 EU member states which include Bulgaria participate fully in the Schengen area once all the agreed conditions are verified and met.