I am the exact same way.
I feel like this is a much more common thing than people give credit for. Vocabulary is by far the biggest fish to fry, yet people always prioritize kanji over it. Kanji is more useful when reading, but speaking or even writing (because Hiragana is a thing) actually knowing the word is more important.
I am currently in a serious low in my study as well and a bit helpless about it to be honest.
My confidence was constantly high for a while but it has progressively vanished these past couple months and my retention is dropping seriously, possibly due to being very busy at work I am not sure.
I tried taking a break from bunpro/anki for a month to focus on reading but it did not help, coming back to it my review sessions rating is catastrophic and I struggle to memorise stuff while it felt like it just happened steadily for the past year.
Not sure taking a break is a good solution then as it will make this even worse, but I think there has to be some adjustments I have yet to find until my brain gets in the right mood again.
I am now trying out 4/5 italki sessions/week to calm down with the constant input and switch to more output, I also keep using satori reader everyday on the side, thatās it.
I think the advice of stopping adding new knowledge for a bit mentioned above might be the way, Iāll give it a go. 
I have been struggling with burnout for quite some time myself. Recently I have been reading a free ebook from Paul Nation about how to learn languages and have made changes to my study routine to reflect what I read in Nationās book. And, frankly, I do feel it has helped me a lot. I think that I was overloading myself with SRS and active study and Iām guessing that youāre probably doing the same thing.
I would recommend giving Paul Nationās book a read. Itās very short, and you will gain a lot in doing so.