Theme suggestion change breaks BC

I misinterpreted where the change was made, so I have no direct fix in mind for this. Maybe taking back the changes in the referenced issue and relying on hook_theme_suggestions_alter might be the most correct way. But if we can't have that (as I for example am a bit hesitant to propose such a change), shouldn't there at the very least be a change record for that original issue?

What possible fixes would you propose at this point?

I think one way to fix this might be to add a hook_theme_suggestions_alter implementation in the module itself to add back the old suggestion. I'm not sure if I can think of other ways off the top of my head. As I mentioned I thought I was seeing an actual theme hook change but actually in https://git.drupalcode.org/project/group_content_menu/-/blob/8.x-1.x/gro... you will notice that hook_theme only defines group_content_menu and menu__group_menu still. So something is still a bit off maybe here in the original change too, I reckon?

Or if I am misunderstanding the whole original change then please inform me. :-) I'm just seeing that the theme hooks in use (using theme debugging via the HTML comments) are different now than they were in the previous 1.x release, without fallback to the old one.