Help me understand a non-predicate sentence

What's troubling us is a subject clause, which is quite a subject and a whole, and the real linking verb or verb is the is after us

Obviously it is not a predicative clause, if If it is a slogan clause, then the slogan should also be a complete sentence.

The translation method is: first translate the subject, that is, the subject clause, "what troubles us" is, the subject, what troubles us " "Yes", this is is the second is, and will be translated as usual

After finishing the above, you should also know that this is not a non-predicate verb, because there is only one verb is

I don’t know if it’s clear