The problem is that Corbyn repeatedly endorsed anti Semitic views, whether it was intentionally or (I suspect) otherwise.
One only has to have a read through this forum and the amount of vitriol targeted at Jewish people is evidence of that.
There was a fringe that was drawn to the Corbyn leadership that came from the Ickeian Jewish conspiracy club and unfortunately their ideas propagated. As ever, trace back where the term ‘mainstream media’ was first used and it’s quite eye opening.
Corbyn was to this mad fringe as Trump is to Qanon. The problem is that he didn’t do enough, or actually understand the issue, that was being created.
Think this sums it up nicely.