What sort of opsec mistakes do you have in mind? Something having to do with the content of the post like PII, credentials, credit card numbers, etc? Stylometry data points? Something about how they/you are posting like whether their user agent indicates they’re using an outdated browser?
Also, whose posts are you hoping to scan? Your own? Are you a Lemmy instance runner who wants to warn your users or something?
What’s your threat model? Who are you trying to guard against and what are you trying to keep them from getting from these posts?