itch.io

Well, after contacting ITCH.IO support, this was their answer (for anyone interested): 

"Hi, I have purchased this game on February 2023, now I got an email about an update for the game, but when I get to the site, it ask me to pay again, this time 8€. Do I have to pay every time the game updates or what? I dont understand."

So seeing @euromancer answers other topics but not people asking this, I just recommend posting a bad review at Trustpilot.com, so they take action, at least, into removing this kind of scams. This is not supporting indies, this is scam people making them think they are actually buying a "early access". 

I buyed the game some months ago, came to check the new update, but... I have to pay for it again??

Awesome. You have gold here, with this game. Keep going and it will be SO famous :)

Planning to go on a road like Streets of rage? With progression maps, more combos, diferent appeareances on the wear you unlock, etc? This game has A TON of potential.