Roles are meaningless, every company have their own. If you think you are senior, you'll put the "Senior..." in your linkedin profile (and CV) to get future offers.

So I don't think you're taking a step back at all (unless you are getting a salary cut as well, then yes, don't do it).

I did exactly the same: I was tech lead at company X (staff engineer) but then I quit to join company Y working just as a normal senior engineer. I got a 20% bump in salary raise... and now I have ahead more levels with the senior level to grown to (and also levels within the staff level as well)... whereas at company X I as already thinking about switching to management (I didn't want that either).

Also, I do always the same kind of job no matter where I am: if I can lead, I lead, if I can mentor I mentor... it doesn't really matter if that's my role or not.

If you're really a leader, then they will notice and will promote you within their imaginary and meaningless career path ladder.