There are better way of sharing files privately than uploading them to some website.
Just use a cloud drive service and encrypt the files with something like veracrypt… You can also use cryptomator which will transparently encrypt and decrypt your cloud drive contents on the fly.
That prevents third-parties from viewing the content but does nothing to hide your identity when sharing the files unless you created the account on TOR using an anonymously created email. Anonfiles’ model seems to be much easier in comparison.
Uploading files to a website is not anonymous either unless you do it through an anonymizing network.
If you share a file to someone, they see which account sent it. If you sent a file through this only the site itself knows and possibly not even that when they don’t keep IP logs.
