Learn Spanish (Latin America): La tienda está cerrada a causa de la falta de higiene. - The store is closed because of the lack of hygiene.

You use a causa de when it is followed directly by a noun or noun phrase, which in this case is la falta de higiene. If you wanted to follow it with a conjugated verb, you would need to add que, for example: a causa de que les falta higiene (because of the fact that they lack hygiene).

Could I use por culpa de or debido a instead of a causa de here?

Yes, both work well! Because a lack of hygiene is a negative thing, por culpa de la falta de higiene fits perfectly. Debido a (due to) is also a great alternative. A causa de just sounds slightly more like an objective, official statement, much like you'd expect to see on a closure notice from a health inspector.

Why use está cerrada instead of es cerrada?

We use estar with a past participle (like cerrada) to describe the result of an action or a current state. The store was closed down, and now it remains in that condition. If you used ser, it would imply a passive action happening repeatedly (e.g., "the store is closed by the owner every day at 8 PM"), which isn't the focus here.

I usually see falta as a conjugated verb (he/she/it lacks). How does it work here?