The main issue is that new cards and Evolutions (specially Evolutions) are insanely overpowered upon release and the game almost always feels P2W.
Besides the fact that Evolutions have significantly lowered the skill required for playing competitively , some evolution concepts are simply unhealthy for the game (like E-drag chain attack and lumberjack having infinite HP).
Moreover , Almost all of the Evolutions are so strong compared to their regular form that succeeding in top ladder with using only 1 Evolution instead of 2 Evolutions in your deck is impossible , not to mention that players are way less reliable on using spells in their deck due to Evolutions which has lead into some of the weirdest and unhealthiest metas I’ve ever seen. For example many bait decks right now only contain 1 spell or don’t include an spell at all !
Other main issues are the clan wars’ system and game’s economy. What i mean is that some concepts like attacking your opponent’s boat in clan wars is completely useless and besides that the clan wars prize is so bad that it almost seems like it’s not worth it at the first place.
Besides all of that , it’s so hard to obtain wild cards unless you already have so many level 14 cards which is absurd and the game doesn’t reward F2P players with wild cards no matter how long they play and realistically it takes so much time to max out a deck if you’re a F2P player.
My English isn’t that good so i hope this helps.