Ourobouros Effect 

Named for the symbolic serpent devouring its own tail; in a political ideology, when members of one group turn on a member of the group on the premiss that the member does not represent or isn't extreme enough for the group's ideology. The Ourobouros Effect is common on both the left and the right of the political spectrum.

"The Huffington Post just ran a hit piece on supporters of Bernie Sanders. Something about 'Bernie Bros.'"
"That's the Ourobouros Effect, man."

Ourobouros Effect by Pyro's R Us October 6, 2016

the ouroboros effect 

When a group, usually political groups, start to fall apart from the inside due to their inconsistencies causing internal conflict. Much like the ouroboros snake eating it’s own tail

The ouroboros effect is really taking hold of the feminist movement

the ouroboros effect by Dr dampness February 8, 2018