Open a file that has no read-only *attribute*, but that is located in a directory that has read-only permissions for the given user. For example, use a document from share:

on Windows, it is at C:\Program Files\LibreOffice\share\template\shellnew
on Ubuntu, it is at opt/libreoffice7.3/share/template/common/internal

Both locations on both OSes are non-writable for non-elevated user. Or an empty document could be created in such a location as a root/admin for testing.

Trying to open a document from such a document in LibreOffice on Ubuntu opens the document in read-only mode (with an infobar), without any dialogs.

Trying to open a document from such a document in LibreOffice on Windows first opens a dialog:

> Document file 'soffice.odt' is locked for editing by:
> 
> Unknown User
> 
> Open document read-only or open a copy of the document for editing.
> Select Notify to open read-only and get notified when the document becomes editable.

On Windows, if the document in such a location *in addition* gets a read-only *file attribute*, like running 'attrib +R "C:\Program Files\LibreOffice\share\template\shellnew\soffice.odt"' as admin, it starts opening the same way as on Linux: without any dialog, right into read-only mode with an infobar.

It is likely because on Linux, the permissions are connected to file attributes, while on Windows, ACL is unrelated to attributes; but the difference in behavior in conceptually similar (same) situations is confusing and inconvenient. E.g., it results in inconvenience (unneeded dialogs) when opening files from read-only locations, like in https://ask.libreoffice.org/t/read-only-is-on-purpose-but-libreoffice-always-ask-what-i-want-to-do/79795.