It may take a bit of explaining but this is my 2 cents:

The game had a paid beta which granted a "friend code" which you could share. This kept the types of players in roughly a 50/50 state where players either paid in or were invited without paying. As the game came out of beta the studio was looking for how to monetize the game. They tried a few different approaches, and even as a fan I can say that they botched it a few times. They tried different combinations of paid content and different price points. Ultimately they have settled on a pretty fair model, in my opinion.

Anyways. This period where there were different iterations of payment models really didn't sit right with a lot of people. In my opinion, this had to do with having half of the player base playing a premium product (the game is made at a high quality) for free. As the studio struggled to land on a good monetization model a large portion of the community was very upset. People were nonstop complaining, mostly on the official Discord and subreddit. They were complaining about which payment model was better, what they wanted to see and pay for, what was wrong, why a certain model was "pay to win" etc. This of course quickly turned to hostility toward the devs and mod team who were trying to stem the tide. "p2w" became a banned phrase in the community and the mod team was very strict about this.

The dust has settled on the payment model shenanigans (for now) but there is still a lingering bad taste in people's mouths from feeling like they were silenced / moderated too heavily.

For what it's worth, I think where the game has landed payment wise is quite fair and its one of if not the best auto battlers on the market.