I've had the same problem since totally switching to
vaping 2 years ago. Dentist said smoking had restricted the blood flow in my gums for 42 years, and now that I'm not smoking...flow is normal, so any "masked" symptoms of gum problems now aren't masked. I've always brushed & flossed though, and haven't had any history of teeth nor gum problems for years, so I was confused. He also said if someone has quite a few crowns or caps, which I do, sometimes the gums at their edges are more prone to bleeding during brushing & flossing. Drinking/sipping on Coke
throughout the day for years was what required the caps/crowns because of enamel wear and erosion.
He recommended getting an Oral B electric toothbrush with those rotating, vibrating head bristles & flossing even more frequently (after every meal). That's definitely been helping with the bleeding during those activities. However, in about the last 4-5 months, sometimes I've noticed a tiny bit of bleeding at the edge of 2 of my crowns first thing in the AM as soon as I wake up, before even any brushing or flossing. I've found that using a mouthwash first thing in the AM has stopped that.