Is this vulnerability defeated if you use a APFS/HFS disk password that no specific OSX user accounts are authorized to bypass, as is the case when you encrypt the whole hard drive and then install OSX versus activating File Vault only on a per account basis? In other words, if I don't have the hard drive disk password, but I do have a single user account login/password, nothing is capable of being leaked in this case, correct?

As the Quicklook database is never decrypted unless you have the disk password in this case, I don't think it is, but would like validation of my thought process as it seems like this mostly pertains to mounted encrypted image files or non-system encrypted drives, not whole disk system drive encryption.

However, if you use something like the MacFort app that stores resting app program data (like your Photos Library file) in an encrypted disk image only decrypted/mounted when you open the Photos app itself (and provide proper password) and then is closed/unmounted immediately after the app that called for it is closed, is this vulnerability still valid? I'm thinking it is in this case, as the encrypted files are at one point mounted on the file system in an unencrypted state and QuickLook can then cache contents as described, but again, I'm curious for validation.