E2E does not protect metadata, at least not without significant overheads and system redesigns. And metadata is as important as data in messaging and storage.
Is it? I guess this really depends. For E2E storage (e.g. as offered by Proton with openpgpjs), what metadata would be of concern? File size? File type cannot be inferred, and file names could be encrypted if that's a threat in your model.
Whom it is shared with can infer the intent of the data.
but i feel in the context (communication/meta-data inference) that is missing the trees for the forest