So here’s the tricky thing with your machine. The USB-C ports are soldered to the logic board, so they aren’t easily replacable. But I WOULD recommend giving them a good inspection anyway and clean them up with some isopropyl alcohol and a cotton swab. It could just be a dirty connection. You’ll need to take the logic board out to see them, but luckily this one is relatively painless (for a logic board) to remove.
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