true:
userPassword/ownerPassword are: Chromium converters (UrlConverter, HtmlConverter, MarkdownConverter) convert(), LibreOffice.convert(), PDFEngines.merge(), PDFEngines.split(), and the dedicated PDFEngines.encrypt() route.
Permission enforcement depends on the active PDF engine: QPDF honors each permission individually, pdfcpu restricts all permissions if any one is denied, and PDFtk supports neither owner-only encryption nor permission restrictions. Restrictions are advisory: PDF viewers honor them, but they aren’t cryptographically enforced once the document opens. See Gotenberg PDF Engines configuration.