eWonLife Hummingbird Feeders for Outdoors, 2 Pack 16 oz Leak-Proof Dish-Style Humming Bird Feeder with Built-in Ant Moat, 5 Bee Proof Feeding Ports, Easy Clean, BPA Free Plastic, Hanging Garden Decor

The one and only fix I have ever seen in this community for wasps and bees is probably something you're not going to want to hear, but believe me when I say I will never go back after implementing. Switch to saucer feeders. Yes, I'm literally saying the only solution is to throw away your current feeders and buy new ones. Every gravity fed feeder I've ever used eventually has bee problems. I don't think it can be helped. Something like this