More confusingly, I first thought of Bette Davis who died in 1989.

Yeah, given the original and the cover of the song Bette Davis Eyes, it's not hard to confuse who's who.

It's (at least mostly) a diminutive for Elizabeth (or Elisabeth more recently) but Elizabeth has declined a lot in the past few decades. I'd also (very anecdotally) observe that diminutives like Liz have probably become more popular than Betty.

Me too and I was confused why the news just made it here, thought this must be a great Rolling Stones article to be trending on HN 5-6 weeks after she passed. Then, oh, nope, that’s not Betty white…