Photoshop alternatives have been making some headway lately:

First, the one everyone knows, GIMP. And yes, it's a steep learning curve, and yes, it's incredibly frustrating. But it's feature rich and (last I checked) the most comparable to Photoshop in what it can do. If you're patient and willing to learn it, it can become a permanent FOSS replacement for you. If you use Photoshop a lot, I'd say this is very much worth the effort.

There's also PhotoGIMP which is an addon that revamps the GIMP interface to make it more user friendly for people that only know Photoshop. Think of it like a translator.

Other options are Photopea: browser based, but is useful for the basic stuff.

Darktable: don't know much about it, seems like it might be more of a Lightroom alternative, but I've heard good things.

And there's the rising star Krita: it was mostly for artists but they're branching out into more photography-based features lately. It's pretty robust.

There's also Affinity Photo 2, which is a true Photoshop alternative in that it's paid software, but it's a one time payment for a permanent license, like Photoshop used to be.