My guess would be that I generally prefer "kiki" sounds and shapes and
Bella is more "bouba". Both "b" and "l" sound heavy and weak to me. If I take a kind of similar name, such as
Beulah, I like it better because the "eu" is a crisper sound than the "e" in
Bella, and I also dislike
Becca because the "k" sound is also weak and breathy but I tolerate it a bit better probably because "k" is lighter than "l".
Then there's also the unfortunate fact the "bela" is a word in my native language meaning "log" and I had the misfortune of watching a skit about this when I was younger. So even my associations are unpleasant (the skit was extremely unfunny).
https://www.behindthename.com/pnl/109883