Futures interview questions

Had a Teams interview which went well . Great dialogue and ultimately was offered a position . Had contract offered which was signed and was all ready to go , then had offer withdrawn on the failure of a background check . Specifically on the social media threads. They use a third party to run the background checks and the in interviewing manager was. It given any detail, I asked if I could challenge the decision and was told yes. I’ve written to the operational manager and explained that without any detail , I cannot challenge this daft decision . No one has bothered to respond so I’m now looking for elsewhere. Would appear that despite my “social media “ accounts being private someone somewhere has decided it wasn’t appropriate . I’ve no idea what exactly this equates to, but reading the company reviews on here , it would appear I’ve had a lucky escape .