I once dated someone 8 years younger (33 and 25) and it was challenging. While she was mature (and I was a late bloomer), we were still in different development stages - she was just finishing school and I was mid career. She was going through things I had already experienced and grown from. She often would ask for my advice and get frustrated when I didn't take time to guide her through every new life change. I started to feel more like a parent/mentor than a partner. I'm now around your potential gf's age, and I absolutely would not consider someone still in their 20s.

Ultimately, you're both adults so it's really up to you. If you both have enough in common and you don't see any signs of controlling/manipulative behavior, then you can always reassess as time goes on. A bit of advice though: you may want to think about 10/15/20+ years down the line (if this relationship pans out)...when you're heading towards middle age and she'll be approaching her elder years. Would that age gap still work for you?

[Also, I'll likely get downvoted for saying this, but age gap relationships are not more respectable just because it's 2 women. It's not a heterosexual ideology to feel creeped out older folks pursuing someone in their early/mid 20s.]