

It seems like a form of age-play.
Age-play is a kink where an adult enjoys some of the pleasures of being child-like. This may or may not be sexual.
However, what she’s doing is involving you in her play without your consent. That’s a big no-no in most kink-like relationships.
My advice is that you both do some research on reputable kink-sites around the nature of kink in general, and then (and only then) explore and read about age-play. I say this because like most kinks there’s a lot of missinformation out there.
Once you’ve done both done some reading, it’s time to open up a proper dialogue around this issue. Part of that dialog will have to be how important this is to both/either of you.
You may be able to ‘scene’ together- that is, have a defined start/end time to this kind of play. It may well be that there are other ways that your partner can fulfill this need, and hopefully your research will have helped you put together some of these. Not everything needs to be fulfilled by the partner. Or, you may find that you have clashing red-lines. That is, it’s something you can’t do, but something she needs, and you can’t find your own compromises.
At that point, you may need a kink-friendly couples therapist. A good one will help you work out how to make this work for you, and ask the equality important questions about what you need.
Do you research well, but do point out that all kink must be confidential.
Somewhere, some poor it tech is about to find out just how good those backups were.