I really, really don’t mean to be rude or inconsiderate here. But I know that’s how this is likely going to come off, so I apologize (and I mean it).
I’ve played Darktide since release day on Nov 2022, maining 2 psykers and playing 1 of everything else exclusively on Damnation (and Aurics / Maelstrom since they were added). And the reason I’ve mained those 2 psykers since the start (for ~1.5k+ hours just them), is because they’ve always been by far the most fun, varied, and rewarding of all classes. They have the highest skill floor & ceiling, a million little tricks to learn, depend more on the basics of dodging, positioning, movement and enemy prioritization than anything else to counter their worst passive defenses… but played right they are ridiculously strong and capable. I know all this, because I have that experience, since release, and know plenty of other psykers and friends who know it too.
Which means I also know what you’re saying is just not true. It may be your experience, but it’s not the reality.
But what has been my experience (and I really do stress, I’m not trying to be toxic here), is that so far every single time someone has come out with a post like this here or Steam or anywhere, where instead of asking for advice or acknowledging they have to learn, they simply state that “psykers are bad” as if it was a matter of fact, every time it’s been people who don’t understand at all how psykers work or how to play them. And virtually every time, they’re not interested in learning either. Instead, they then go on to complain about various abilities or weapons or blitzes and demand they be changed to what they expect, instead of expecting themselves to learn. And I learned the hard way that there is no sense discussing anything at all with such people.
I’m not saying that’s you, maybe you were just frustrated and used a hyperbole you didn’t really mean in your OP. And that’s fine, I have bad days and bad moments too (today is one in fact). But psykers are not horrible in high difficulty play. They are the best at it. But they do require a whole ton of skill, experience and knowledge and ofc gear too.
I hope you will have an open mind and desire to learn. If you do, ask what you struggle with and I and others will do our best to help. If not, then it may not be the class for you. And that’s ok too. 