Games that hop onto hype/trends that are currently active, specifically things that are like NFTs, cryptocurrency craze, play to earn and other things because you want to get that money any way possible, stability and loyalty of customers be damned. I am not talking about Patreon/subscription based payments because those are fine unless developers are very pushy about it in their products, just talking things that relate to you know, chasing the big money right away.
On more quality based criteria, stereotypical writing with man/woman characters who fall in love in first sight, good vs evil stories that do not see the greater picture, harems of any kind, generic isekais no matter how "edgy"(like endless rape)or "goody"(loser turned into god saves the world in a single swing from dumb evil)they are, basically anything that doesn't raise post-product questions about how good the product is.
So yes, worst things can range from game's quality, like execution of its topics, design such as world and writing, to something related to systems and how it's made, like packing extra payment options in form of microtransactions(only practical one for free to play for understandable reasons), or even worse, things I mentioned above, and while everything overall is up for discussion, let's just say there's a good reason why people may dislike or hate them.