OOF. Typical Costa Farms. The soil mix they plant their stuff in is horrible. Its holds way too much water. I think they do it because they know that the stores they ship to will either water very infrequently or never water at all. If they get a store that actually does water, the plants can get overwatered easily.
Birkin is tough. Unpot that and shake off as much of the old mix as you can. DON'T wash the roots. Snip off any obviously dead roots.
Repot it onto a much smaller pot (only as large as the root system needs to be container plus an inch). Make a mix of good quality potting soil (1/3) orchid bark (1/3) and perlite or pumice (1/3). repot and water once, then water maybe once a week if you are keeping this int he house. It should bounce back. If you start to see any leaves like this, don;t fret. That is the natural genetic expression of the Philo Rojo Congo parent
I bought this Birkin about 4 years ago, it has done pretty great in the soil mix I shared above. I'm currently training it to climb this pole (which is unnecessary, I just want to do it LOL)
