I'd say that it could be confusing, since people often "Stand in solidarity" without any actions, but "Giving mutual aid" is something active, like protesting, monetary aid, a large scope if things.

Anarchists seem to think they have a monopoly on mutual aid, but it turns out that police agencies are all about it as well. At least where I’m at, people think that mutual aid is the secret sauce they have to defeat the efforts of the state, not realizing that just in Portland they have the city, multiple counties, Metro, and several neighboring suburbs strategically sharing resources and cooperating, even across state lines.

I observe that mutual aid between well-structured and stable organizations of well-trained people is even more effective than mutual aid between lone actors and temporary self-organizing cliques.

In French you would translate solidarité and entre-aide respectively each term, so they worth having each a dedicated word.

Actually I was surprised when I wanted to find a straight forward equivalent to "entre aide". It seems that "interhelp" is sufficiently obvious for having an organization taking this name, but this apparently not an idiomatic word per se.

Mutual aid is a fairly common term in my region:

https://www.lpm.org/news/2022-11-27/eastern-ky-mutual-aid-gr...

Solidarity usually means a specific action - e.g. joining a strike action, critical support, organizing, etc. Mutual aid usually means intra class action.

Mutual aid is right now innocuous enough to act as a pretty good left-wing shibboleth. Depending on whether a group refers to their activities as "charity", "service", or "mutual aid", you can get a pretty good idea of how left-wing the general consensus of the group is.