After a little more testing, it seems that for the Permalink field in the Edit Plugin Filter page, this:
A) https://mydomain.net/
is NOT the same as this:
B) https://mydomain.net
3 tests:
1) When I use A) without checking off ‘Also affect children’, I expect that a plugin will be filtered (e.g. turned off only) for the homepage.
But in my test, it was filtered for the homepage and other pages, but not posts, as if I had checked off ‘Also affect children’, so I think there’s a bug.
2) Similarly- when I use B) without checking off ‘Also affect children’, I expect that a plugin will be filtered (e.g. turned off only) for the homepage.
But in my test, the plugin was NOT filtered anywhere, as far as I can tell- not the homepage, not other pages and not posts.
Although technically A != B, I don’t think it’s reasonable to expect users to remember a trailing /, so while perhaps not a bug, this should be changed IMHO.
3) If I use A) and check off ‘Also affect children’, I expect that a plugin will be filtered (e.g. turned off only) for the homepage and other pages, but not posts.
And in my test, that’s exactly what happened.
4) If I use B) and check off ‘Also affect children’, by this point I frankly don’t know what to expect, so I’ll guess and say ‘nothing’, just like in 2) above.
And my test shows that I guess right. No big surprise there, it’ll depend on how you handle 2).
So to sum up the answer to my question AFAIK, with v4.1.1 I don’t see how to enforce a filter on the homepage only.