Honestly, it's a lot easier to believe that it's aliens and not "illegal miners with jetpacks". Seems like an even more ridiculous explanation.
“Illegal miners get their hands on some surprisingly niche tech” seems many many orders of magnitude more likely than anything related to aliens.
I probably couldn't do that for the full 10 minute flight time though.
It is not some bootleg mining to scrape by.
Would be interesting to corroborate whether unusual noises are associated with their arrival.
Sound doesn’t reflects well of water so if you can easily mask it by flying close to the water and quickly jumping over.
Money motivates+enables narco-traffickers to acquire some pretty amaze-level tech. So why not miners too ?
Not to say that "aliens" is necessarily less far-fetched... but it's up there for sure.