Collaborator has shared a draft paper with a significant amount of self-plagiarism. Should I say something?
You do not need to make a fuss, or mention "plagiarism". All you need to do is to recommend adding a reference to the copied paper for each paragraph in question. That is a legitimate review comment, proposing an improvement in the draft paper.

Andreas Blass, in a valuable comment, suggests something along the lines of "The following description of our methodology is taken from [17]" or "Our methodology is the same as in [17], described there as follows" is adequate, without needing to also put quotation marks around the quoted description.