I'm not surprised by this.
Readdle's apps, namely 'Documents', have always been my go-to on iOS for editing PDFs and transferring files[1].
But they went and added a useless VPN to Documents, then released a 're-design' which cuts functionality (and from the reviews is quite buggy). It's sad to see a quality app degrade as the developer adds bloat and new 'features'.
1: For example, Documents (which edits PDFs as well) has a built-in WebDav server that is super useful for getting files between an iPhone and a Linux machine over Wifi.
1) Defaulted to setting PDFExpert as my PDF viewer,
2) followed with a survey I could not close out,
3) required an account to begin.
I'm happy it works for you but I'm tired of the modern software that wants accounts, your data....