Mine similar case.

Admitted due to covid stay icu and had to use ventilator.
After awhile dr say turn off ventilator coz getting better can talk and move abit.
Suddenly next day dr say condition worsen back on ventilator and got kidney infection until need to do dialysis.
After few days dr sy not good already body cannot tahan and resuccitated few times.
Then gone liao.

Im thinking hospital negligience cause infection kidney failure.
But later read macam covid may cause that too.

Want to ask lawyer but gonna cost money even before start investigate.