I've written before about Jeremy's questionable connections - some of which can be ignored, while others are more serious. But on Panorama itself, yes, it was a pretty poor piece of journalism. There was no pretense of balance and impartiality. But evidence of BBC bias? Yes, but not in the way most people complaining about it on social media think so.
In recent years, Panorama have done hatchet jobs on Nigel Farage and UKIP, Unite and Len McCluskey, domestic Islamists, George Galloway, and not so long ago Nick Griffin and the BNP. If the BBC was biased against Corbyn, then why have they produced equally shoddy pieces about people who aren't on the left? It's because the BBC's bias tilts toward established politics. That is the centre left and centre right, and the industry that turns around Westminster and press hobby horses. In the absence of democratic input into BBC programming and content, but also direct government interference, could it be otherwise?