User option to disable Proton Drive link sharing
The ability to share content from my drive makes me uneasy, in case I did this accidentally. I would be much more comfortable if there was a setting to disable all sharing for the account if user desires.

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DM commented
I would add - it doesn't have to be account-wide, but more granular. E.g. there may be a directory, where I keep my passwords, licenses, grandma pics and so on - I wouldn't ever want to share them, and accidental sharing would be a big problem. So, it would be great to have a "sharing lock" option on directory, so that this directory and all subdirectories would not be shared, and any existing share would be invalidated.
If applied to root folder, that would basically do what OP wanted - disable sharing for any files.