Her past relationships are part of her life. It is her past.
Having some memories of this past is okay as long as this does not keep you from evolving together.
If you don’t want to see these pictures, ask her to keep them with her own stuff. Fair enough!
I mean, would she be pleased if you were hanging a picture of your ex on the living room’s wall?
It is healthy for her to do what she wants with her personal stuff.
This is a place where she has the right to express her control.
Let it go and don’t be bothered. That’s of course unless all this is in your face. Then it is okay to tell her.
Put it this way: even though she keeps some pictures of her exes, it is with you she is today.
This is what you should always remember.