I mean,
Isabella has been on the rise since the mid 90's and is still in the top 10 so I don't think it's had an usually short run. That's 25 years including 16 in the top 10.
I don't know very many
Bella's who are just called
Bella, but many many
Isabella's,
Annabella's, etc. so it still feels very popular to me.
It is cutesy and cheesy to me. I don't like it and I am sick of hearing it.