it looks like a wild mint. is the aroma minty? are the stems roundish or square-ish?

Spearmint rather than peppermint I think

If this is mint, it should really be outdoors and definitely needs a larger pot or tub. It likes to send out underground runners so it wants all the sun & space you can give it. We have this growing wild in a wooded area near my house and walking on it fills the air with minty aroma. It seems to repel vermin because I never see any damage or bug infestations. It's really nice in homemade lemonade. Makes a delicious & refreshing summer drink.

Agree it looks like a mint of some variety, especially if the stems are square rather than round. Unfortunately, it shouldn't really be let loose in the garden, because it spreads widely by means of underground stolons or runners, and will be popping up all over the place unless contained or restricted. If it is mint, its probably wise to dig it out ...

It is very invasive in open ground! Best grown in a container. It's really hardy too, you can forget to water it for months & it'll survive.
I had some on baby spuds with lunch😊

When we stayed at a friend's French watermill, there was wild mint growing in the lawn and the smell was wonderful when we walked on it or cut the grass.