Zack Snyder left WB 6 years ago. There's been 10 DCEU movies between The Flash and BvS.
If BvS is to blame for DC's image in 2023, that only means the last 7-8 DCEU movies did nothing to improve the brand image. Were they so mediocre/bland? Mind you, ZS has been gone a long time, these new movies have been critically well received, championed by DC fans as "step in the right direction", and WB has incorporated all the things fans vocally complained about like light tone, humor, bright colors etc, nostalgia etc. Yet, its the early DCEU movies that made money, and the latest batch of movies have all have lost money.
So either the "Hamada-verse" was a failure as a "course-correction", or maybe a 8 year old movie is not at fault here. Mind you, Wonder Woman and Aquaman all came right after BvS, and were big hits. Its time we stop scapegoating, and place the blame where it really lies, WB. The Justice League mess, scrapping the shared Universe for low budget solos, massive cuts in editing, trying to ape MCU, the whole thing has been a mess.
The DCEU was never meant to rival MCU as this neverending 20 film shared universe, it was a 5 chapter story, accompanied with solo spinoffs. Changing courses wildly midway was always going to fail. Should have just released Snyder's 2h45m cut in Nov 2017 and rebooted.