You dig deeper and tell everyone what you found. For the laptop story there was nothing to be found.

Verification takes time, when someone dumps a ton of information publicly and exclaims it is true there is no avoiding some people believing it no matter what happens.

If we are afraid about censoring that being transparent about what is censored and verifying it afterwards can help with that.

However I don't think there is a true solve to misinformation. Lies are catchier than the truth after all.