What are some signs that a girl is using you as a rebound to temporarily forget about her ex?

Last year I was a rebound and my dumbass didn’t realise it. Of course never forget about all the AWALT, holding frame, non-neediness etc. However, it was my first time properly with a girl and losing my virginity (I was 17) and I let myself slip a bit.

Ideally, I feel like this shouldn’t be a problem as you should spin plates to not get too attached to any one girl, but I’m just curious. Has anyone ever been a rebound?