Why is my snake plant dying?

I have a snake plant that has been generally growing ok. But I shifted it from an open area into my home (as I’m staying in an apartment now). I placed it at an east facing window (which has a 7% VLT film) and had only water it once in the last 3 weeks. But suddenly 2 of the leaves became limp and 1 of the biggest one is turning yellow from the middle.

The 2 that became limp was removed and I found that the roots were all gone.

It seems like a few are also getting limp but I do not think it is overwatering. Is there a reason why? What can I do with it?

Note: I’ve shifted it to a west facing window (with no film) but that is not the ideal place for me to put plants.