EFF, who I do follow, has not criticized the withdraw.

I don't know enough about Bernie or Clinton to know where they stand on the issue. Clinton's de-endorsement was probably not genuine so I'd bet she has criticisms of the withdraw.

My main point is that an issue that was popular on the left (enough for Clinton to flip-flop on) seems to now be mostly the voices of the left criticizing the withdraw.

There might be some bias there because people who did support withdraw might be less incentivized to vocalize support for policy that landed in their favor.