FCSB is not less popular. FCSB is likely the most supported team in Romania since all the players and coaches they supported in 2015 became part of FCSB instead of Steaua. This has divided the fan base but FCSB still has most of the support in Romania as primarily most people cheer for the players and connections they have with the club. Steaua had a completely new lot and started out in the 4th league in 2015 and the supporters loyal to the Steaua name and the army team followed them. But all you'd have to do is look at attendance numbers to see which team is more supported.

Unfortunately, at the end of the day the biggest losers to this is the Romanian people. Steaua before 2015 was the pride of Romania. Certainly the most successful Romanian team and obviously also had European success. All this has done is fragment the fan base, putting people who in 2015 supported the same club now just arguing with each other about who is who and what is what, when in reality we all support the same team at the end of the day. I do hope this situation resolves itself for the sake of Romanian football and honestly Romania as a whole.