How to fix this situation
A little backstory to my situation:
About a week ago maybe a little longer, my tank had a co2 overdose, not an end of tank dump just a ton of co2 built up in the water in my reactor without me realizing it while I had the filter off doing maintenance.
From what I could tell I saved all of my fish after realizing they were almost dead, only I didn't and one corydoras habrosus died from it in one of my stem jungles unknown to me.
The next day it looked like my tank had crashed almost all of my plants were either melting or just looked like they were dying and the tank water smelled weird, not bad just weird.
I checked all of the water parameters I have access to and nothing was out of the ordinary, 0 ammonia 0 nitrite ~10 nitrate after dosing kh&gh were the same as always and PH was unreadable because of the co2 being on but the drop checker looked good.
Fast forward to today and I'm looking at my tank still wondering what is causing this massive melt and I see it, in one of the stem jungles the remains of a cory which I assume died because of the co2 overload.
Could a dead fish be the cause for my mass plant melt?
Growing in the melting plant leaves is a weird white hair/thread algae that isn't growing anywhere that isn't melting, is this because of an ammonia source in the tank?
Now that I've realized the death and removed the dead fish will the plants stop melting or is everything likely to just keep melting?
What steps are recommended to fix this issue?