Donald Trump may have just undercut his own legal defense with a posting on Truth Social, and the site’s users were quick to point it out on Saturday. Trump, who is currently petitioning the Supreme Court for full presidential immunity even in instances where conduct “crosses the line,” took to his soon-to-go-public social network this weekend to decry what he has labelled political prosecutions against him. Trump has claimed without proof that all his civil and criminal cases are brought because of President Joe Biden. ALSO READ: A neuroscientist reveals how Trump and Biden’s cognitive impair…