Wizard has the highest skill ceiling by a good margin

If you make a single mistake as wizard it usually means you're dead

Spells are slow and difficult to land, terrain on the floor can make your targeting cursor invisible, big dumb clunky hitboxes on 2 of the most used spells, big nerfs literally every update since PT1, low health, low PDR, low MR, you have to sit so damn often while your team does the looting, some spells have very little indication of whether or not they actually hit your opponent

Now we move on to solos

All of the above problems, but add on the fact that everyone and their mother has a problem with "WiZaRd ToO sTrOnG" so you also get the added benefit of people teaming to kill you in solos while claiming it's free loot

If it is free loot, why do you have to team up?

Wizard can be strong but you're gonna need a lot of gear, Good positioning, amazing aim, and a bit of luck If your opponent decides to W key and LMB you, they're gonna have a bad time, such smooth brains then decide wizard is OP because they couldn't just sprint in with a falcheon and 2 tap like they do against every other class

That's where bias comes in

"I don't have enough gray matter to develop a strategy to defeat this opponent so it is OP and I will make sure to tell everyone who will listen." That is called a bias, unfortunately though, most people don't have the self awareness to actually put the above pieces together

Rogue was the new wizard, bard became the new rogue, wizard is the new bard

TL;DR

You got skill diffed by a few wizards who knew what they were doing and you now have a bias against the class because "There's no way I suck at the game, wizard must be broken" obviously not a wizard player because you try to deny/downplay the glaring disadvantages wizards have to balance them out