Etheria Restart, is not just a gacha, is a PVP gacha, which in on itself is a taboo.
It initially sold itself as a f2p friendly PVP gacha, but, after released, it does the usual gacha thing of forcing into a meta, no biggie just reroll account, but then, they did the other gacha thing of having new characters be stronger than the older ones, AND they nerfed the ones which were strong initially.
Normally it would be the usual in a gacha, the problem comes from it being a PVP, with big spenders (whales) being the dominant ones for obvious reasons.
As, the game not only requires you to have dupes for characters to be actually usable (and getting dupes is gambling), you also need tons of materials for leveling then up, which are time gated unless you wanna spent, this is normal gacha design, and we don't mind it on PVE gachas.
But, PVP gacha is another story, with whales winning tournaments, and just flashing their cash over anyone, so, of course, most low spenders (dolphins) and f2ps went away as its imposible to engage on the PVP without forking a fortune. Can't engage on PVP... On a PVP gacha, the problem is obvious.
Didn't help that the story sucked, and it required you to invest on the account if you wanted it to be less tedious.
Edit: If memory serves, Shadowverse had similar issues, but that one is a digital TCG.