I wanted to add something outside of what I marked as a solution.
Basically, the issue was that Unraid decided that my parity disk had problems when it hadn't.
Just because one single write failed, it decided that the disk was dead and therefore disabled it.
By doing this, the array was put at risk, once again, for no reason at all.
Unraid should've been built to protect your data, instead it tried to temper with it like a malware. This is terrifying.
Disabling a drive just because one single write failed (that could happen for a loooot of reasons) does not make any sense and I hope you all see that.
Run a check on that sector and keep the drive active.
If write operations fails frequently, then you can think about disabling the drive.
I am growing tired of the lack of documentation, of the lack of official support that this (paid) software has.
In fact, this forum was not able to provide any concrete solution and help outside of something very basic and, to be precise, 90% of my post was just ignored.
I really cannot recommend Unraid anymore, unless you want to risk losing your data without any failure and want to troubleshot it with a UI that gives out useless messages only.