What happened to Google+ Communities? Many are missing

What happened to Google+ Communities? Many are missing

Do you use Google+ communities regularly? I use them all the time. Every day. Either for myself or for my clients. And I mostly use YouTube / music communities. But just recently, (in the last few days) where I've gone to post to them, many of them are missing! I don't know what's happened here. Whether they were removed by Google or perhaps the owners. I doubt the latter since those owners of them would probably all be different people. And they wouldn't just remove them for no reason. But now when you search on Google+ for YouTube, it only shows a very small amount of them as opposed to showing lots of them.

But as you can see, it's only showing about 10 YouTube communities. Where as it used to show a LOT more!

I don't know what's happened here. Why they have gone. Whether they were removed by Google or the owners I don't know. I can't see how Google would remove them. Some do get some spam but spam posts are usually reported and removed by the owner. Or perhaps Google has removed them. But then, why only some and not all of them?

Does anyone know what's happened and where they've gone?