@Constantine
Consistent result: Shift-Command-v executes ‘paste unformatted’ in every app I’ve used it in EXCEPT Only Office. (It is, in effect, the same as the Windows kb shortcut, substituting the Mac’s ‘cmd’ key for the PC’s ‘ctl’ key.)
Also consistent result: Option-Shift-Command-v has no effect at all. Nothing happens. (Not only in OnlyOffice but everywhere else I’ve used it.)
From what I’ve gathered so far, the ‘option’ key is used when text (or a file) is to be ‘moved’ rather than ‘copied,’ but as stated I’m not finding it does anything in Mac OS Mojave (10.14.3). I have seen other posts about Option-Shift-Command-v not working, including by a Catalina user. Even if the key combination appears to work in Ventura, please check to make sure the text is actually being ‘copied’ and not ‘moved’ (i.e., deleted from its original location). Thanks.