macOS Monterey ups the game for the Preview app in a subtle way: you can better control over PDFs. In Big Sur and earlier releases of macOS, you had to rely on Adobe Acrobat or another PDF-editing program to set controls.
Now, Preview in Monterey correctly lets you create an owner/permissions password and pick which elements of a PDF may be modified and whether it may be printed by those who receive the PDF. You can also set a separate user/open password that must be entered when opening a PDF to view or act upon it; previously, this password was the only option available in Preview.
These changes also explain why Monterey disabled File > Export as PDF: Apple now better observes the permissions embedded in a PDF. Before Big Sur, you could choose File > Print and then Save as PDF to get around these restrictions. In Big Sur, Apple blocked that pathway, but still allowed File > Export as PDF. In Monterey, PDFs locked against file modification or printing can neither be printed nor exported to create an editable file.
Read more at Macworld.com