Skip the fake free stuff like GIMP or Photopea if you actually want something serious - they're nice for poking around, but they'll get on your nerves pretty quick when you're looking for basic features.
Affinity Photo is the obvious choice for you. You pay once (around 70€ or so), no subscription that comes back every month, and honestly it's solid for retouching. The interface isn't that far from Photoshop so you'll get the hang of it pretty fast. There's also Affinity Designer if you want to get more serious about graphic design, and they often sell both together as a bundle at a decent price.
Otherwise there's Capture One for pure photo retouching - it's a classic with people who do photography. Corel Paintshop still exists too but it's not as trendy as it used to be. The thing is you get a license once and for all instead of paying 60€ a month forever, and that really makes a difference over a year or two.