Can your cloud provider read your files?
Almost every service says your files are encrypted, and almost every service is telling the truth. The question that decides whether it matters is who holds the key. Pick the one you use.
Using something not listed? The question to ask its documentation is whether encryption happens on your device or on their servers.
How to read these answers
"Encrypted at rest" means the provider encrypts your files on their disks with keys they control. It stops a thief who walks out with a drive. It does not stop the provider, its automated scanners, or anyone who compels the provider to hand something over.
End-to-end encryption means the key is created on your device and never sent. The provider stores bytes it cannot turn back into files. The cost is that nobody can recover your data if you lose your passphrase, because nobody else ever had it.
The longer explanation