This seems to happen a lot - it might not even be your fault, just someone decided they didn't like your videos and filed a bunch of complaints, or an algorithm

This seems to happen a lot - it might not even be your fault, just someone decided they didn't like your videos and filed a bunch of complaints, or an algorithm misinterpreted some speech. Once the automation sides against you your only recourse is to hope to generate enough social outrage that a human takes notice. The lesson learned is always that YouTube should never be your primary data store, you need to keep the best quality copy of your video in S3 (or similar) so you can rebuild when needed.