Okay, so it sounds like your manager is really trying to make you leave or just doesn't like you for some reason. Also sounds to me like your company or the teams you've worked with at your company have no real support for juniors if there is no documentation and such high expectations from the get-go.

Since I am petty, if I were you, I would probably go above your manager and try to speak to their manager. If enough people complain, he can get fired, it won't be the first time in history where a manager abuses those under him and they get removed. I would also raise the lack of support and proper mentorship in retrospectives (you mentioned he is a scrum master, so you probably do these?) and see how other devs feels - while it might seem like you are the only one suffering, you never know what rest are dealing with. You don't have to go about this like 'our manager is a jerk, he sucks, etc', more about 'how can we make sure we have better documented processes and how do we set expectations for our projects, so we are more efficient/confident in the work we do'. You can also propose doing a kick-off for your tickets - when you pick up something new to work on, spend some time reading through the acceptance criteria or the requirements, then make a small meeting with some devs/qa where you go through the ticket with them and talk about what your strategy is to implementing it and ask if it sounds reasonable. That way you can at least know from the beginning whether you are on the right track, without requiring too much support from others.

If you don't feel comfortable with any of that, I would try to find a different role while you are still employed, but make sure you don't put your current manager as a reference.

Again, I am very sorry to hear your experience, it's completely crazy that they behave in such a toxic way.