" Because of" is a subordinate conjunction at the start of a sentence.

David Bray

when I web searched, I learned "because" can be a bit of a chameleon, but if it's a conjunction and starts a sentence, it is always a subordinate conjunction. The structure report said the sentence below started with a coord conjunction.
Because of superb teamwork, hard work, tests and fixes, and retests, it has no major weakness.