The way War Mode splits community is such a bizarre and dated concept in 2020, when you consider that all major gaming companies try to unify communities nowadays with cross play and cross platform features.
It’s such a PITA always having to keep checking War Mode state when I want to group up with friends or strangers.
I don’t have a problem with War Mode in particular, I just dislike the way it makes grouping up incredibly frustrating.
If frustrated, the best thing is to take control and form your own groups. Name your group “XYZ WM OFF/ON”, simply kick random joiners that ignored the title. For friends, pretty easy to discuss WM off/on in advance.
An addon like this could be handy if it still works: https://www.curseforge.com/wow/addons/warmodeprint