Reasons eGFR would rise and lower so drastically and quickly?

New to this forum and very happy to be on here!
So, I'm actually writing on behalf of my mom, who's not doing good at all. And apologies a head of time for the long post, but a lot of perninent details behind this and we desperately need any kind of help we can get and my mom's life is depending on it.
Long story (kinda) short, she was hospitalized a little over 3 wks ago for Covid Pneunomia, and unfortunately now on a ventilator and intubated, and we think the hospital has only made her condition worse and continuing to do so.
We have been trying to transfer her since before she got on a ventilator and this hospital is doing everything they can to prevent her transfer and for her to stay in their same hospital system (and trust me, we've tried everything and still trying, but that's a different story).
We have also caught this hospital not telling us the truth the entire time and not only do we have proof of it, we got them to finally admit to one of the time, but again that's it's own story.
So about a week ago out of no where, she suddenly started having kidney issues for the first time ever, and her eGFR dropped so dramatically within a day, when it's been fine the entire time at this hospital. She suddenly, in 1 day, got the point of kidney failure and is also now on emergency dialysis, on top of everything else.
It's been like pulling teeth for her doctors to talk to us, let alone answer any questions, and the only thing we can get from even her nurses is just "Oh, Covid does that." Which obviously doesn't answer our question, but also it's a little too fishy with the timing of it all and looking at her test results, ect.
She's been in normal range her first two weeks, then the 3rd week on 8/27 @ 6 AM she was at a 90, then....
8/28 @ 4 AM she was at a 78
8/29 @ 4 AM now she's suddenly at 36 (what's weird after this sudden drop, they decide to wait even longer in between each test)
8/ 30 @ 1 AM now at 17 (testing now 14 hrs later), the same day @ 4 PM now she's down to 14, and consistantly dropped down to 12 that night. And with that consistant of a drop in one day, after 4 PM that day when she got down to 14, they suddenly were checking more frequent again, so they knew what was going on and still didn't do anything about it, to where it just kept dropping.

*Also, what's weird too is that it's been only at night with the night time staff when she consistently gets worse and it's an uphill battle each day (for 3 weeks now and this has happened with both hospitals).
Along with that, no body called us when she dropped massively to 36 that one night, until we saw the results ourselves the next day and called and tried to get an answer, which we couldn't, then the next morning at 1 AM when she dropped to 17, they still never notified us (and we told them to always call us no matter what time), it wasn't till we went up there that same day early afternoon and they finally told us in person that now she's having kidney failure out of no where and needs emergency dialysis. Almost like they were purposely waiting for her to get worse, cause she was and why wouldn't they call the family?

We don't want to think negative with this hospital ever, especially with them caring for our mom, but with all things considered, it's too much that doesn't add up, so we are just trying to plug in the missing pieces. It's our mom's life that's at stake, so we are doing everything possible to save her and just trying to make sense of it all, while not getting any answers from her docs, to head nurse, to anyone.

She got transferred later that night to their sister hospital (against the families wishes- another story in itself), but we got her on CRRT and she's somewhat stable and her eGFR levels have improved, still up and down, but definitely not as drastic as before.

My sister talked to a friend of a friend Nephrologist and it all seemed weird to him too and unless it's a medication or something they are doing, it's not possible for the numbers to rise and drop that frequent and drastic, or something could also be wrong with their testing.

So, now trying to do our own research and we've read it could be from blood pressure medication to dehydration (which she was dehydrated when she was Careflown to the next hospital), but with all things considered above, what else could be the reason (besides Covid) for such a drastic rise and drop, and in such a short amount of time?

She is on blood pressure medication and they have had to change amounts to the types because of the amount of her oxygen and we are looking into that and her other medications, but in the mean time, seeing where I can reach out to hopefully get any feedback or help, before it's too late.

Thank you in advance to anyone that made it through this entire post and can help in any way at all.