OP can't prove that. The only way is to scrap the server completely and start with a fresh OS image. If OP has no backup and ansible repo (or anything similar) to configure a new home server quickly, then I guess another valuable lesson was learned here.
Especially when it comes to my home network, I would rather be safe than sorry. How would you even begin to investigate a rootkit since it can clean up after itself and basically make itself invisible?
Particularly when it comes to Kinsing attacks, as there seem to been rootkits detected in tandem with it, which is exactly what OP got hit by it seems (although they could only see the coinminer).