Rules for writers, Tenth edition - Diana Hacker, Nancy Sommers 2021

Do not use a comma to set off a concluding adverb clause that is essential for meaning
Unnecessary commas
Punctuation

When adverb clauses introduce a sentence, they are nearly always followed by a comma (see 33b). When they conclude a sentence, however, they are not set off by a comma if their content is essential to the meaning of the earlier part of the sentence. Adverb clauses beginning with after, as soon as, because, before, if, since, unless, until, and when are usually essential.

When a concluding adverb clause is nonessential, it should be preceded by a comma. Clauses beginning with although, even though, though, and whereas are usually nonessential.