It won't be any easier now that the pause in use of the Johnson&Johnson vaccine has sown fresh seeds of doubt. (From The Economist)
Which type of clause is the bold one?
I don't think it is the real subject of the main sentence, in which "it" is the dummy subject.
I also won't think it's a relative clause, for no proper antecedent is preceding "that." Besides, the sentence after "that" is complete in itself, it doesn't need "that" to be a grammatical component in the sentence.
It makes more sense if the clause is relative clause though, but because "now" is a time, the relative pronoun "when" will have to be used rather than "that."