As someone, who has tried a few graduate jobs in my time I can honestly say that I faced similar issues. I think some workplaces, especially these top grad schemes, can expect a lot without necessarily being the most supportive to anyone that struggles. I certainly found myself in a sink or swim situation on multiple occasions and despite asking for support or seeking work from my line manager, I absolutely dreaded work and couldn't wait to get out of there.
Firstly, try and seek support and maybe ask your manager, what you need to work on and set some targets you can work towards. If you're also struggling mentally, don't be afraid to seek medical advice as it can I know how the anxiety and dread of work affected me.
If things are still not working out, you may need to consider if this is the career path for you. As someone got an Engineering degree with the goal to get into Engineering, I worked hard to get several different roles in the field. I first completed a placement year in one sector and this is where my problems started, I absolutely hated it and would have quit if there wasn't an end date. I then got a graduate job after leaving uni and only lasted a few weeks, granted COVID was also having a significant impact on my mental health but it was not working at all for the same reasons. I then applied to another graduate job in yet another sector and I faced the exact same issues again and the dread and fear of work only persisted. It was the third time that I finally decided that Engineering careers were not for me. It was a hard and terrifying realisation to come to as the thing I had spent basically all my life working towards all fell through. I felt like a total failure and it certainly took its toll on me mentally.
Now I am currently in a role in an entirely different sector (teaching) and all the fear and hatred of work is gone. Sure, it's hard at times and certainly challenging but I am thriving so much more and while it was hard to come to that choice, it was absolutely the right thing to do! I'm not saying throw the towel in just yet but don't worry if this isn't the career path for you. If you've given it as much as you can and its not working out then it might not be for you. I went through a lot of doubts, fear and worry when I should have listened to my gut instinct the whole time. You can't hate work to their point of dread as you are going to be doing it for a significant part of your life.
Sorry for the wall of text but, just wanted to let you know, you're not the only one who has felt like this.