I believe taskbar grouping is mandatory on Win11, on Win 10 it's optional and IIRC by default its Never (which is what you probably have). I have it set to Always.
On Win11 it will look something like this
only in the middle (sigh).
Calibre is highlighted because of Winkey+T. ↓↓↓.
I can't recall if it was with you, but I had a recent exchange with someone here how users these days want every app to do every little thing.
FX: I believe the upcoming release of Sigil will allow users to park its Spellcheck and Reports windows in the status bar.
BR
PS: I suspect OPF Helper would appeal to the Sigil community.