Since others already suggested mostly on-topic suggests, here's an alternative suggestion:
Instead of looking specifically for a mentor - look for an open source project that you can help with. Ideally one with a discord or something to it's easy to be in contact the the lead dev. A lot people don't mind mentoring juniors, but in my experience it doesn't happens that explicitly - "be my mentor" - and it might sound like you're asking them a lot.
If you invert it into "Hey I wanna help you with your open-source project, but I don't really know what to do, what your expectations are, how to implement a specific feature" - then you're offering to do work them, instead of asking for something. And implicitly you'll get mentorship in return.
And "real" projects probably also look better on your github / portfolio than only some dummy projects for learning purposes