I’m sorry you’re feeling like this but as others have said, I don’t think you’re alone. DH started a new job and total change of career not long before COVID and is struggling too - it’s not sales but sales-type targets which make everyone out for themselves and not v forthcoming in terms of help.
Being out of the office just exacerbates all of this - so in DH’s case, where he might just ask for help if someone was passing his desk in the office, this is a whole load harder remotely. So he’s struggling to learn the systems and ‘ways things are done’.
The same goes for you in this scenario - in the office, you might ask for a quiet word with your manager and get it all sorted out before you go home. Remotely, things are left to fester as there’s just not that ease of communication.
As PP have said to you here, and I’ve said to DH, why would they want to get rid of you? Even if there are some issues, if someone needs to do the role, it has to be easier to keep someone who’s trained and on-boarded already. So try not to worry too much about that.
It’s really rough at the mo - people are just missing out on those interactions that help to reassure them everything’s ok. Or to lessen the effect of negative feedback.
Sorry, this is long, but it all sounded so familiar I just wanted to say you’re far from the only one feeling like this. Try not to worry and I hope it works out ok.