Holdo actually tells Poe that she has a plan in the comic adaptation

Oh, I thought there wasn't a single criticism that was valid, Rian? Looks like your own peers thought otherwise. What a jackass.

Still the same issue. She doesn't tell him what the plan is in either adaptation.

So he gets demoted for costing them the entire bomber fleet while all Holdo does is actually cost them the entire actual fleet.

Who wrote this comic?

All you need to do is have Holdo have two or three separate trusted groups doing their own missions unbeknownst to anyone outside of Holdo and her closest consorts and Poe potentially messing up their missions which would see the Resistance get away and be up with regards to battle information or tactics. His wings are clipped because he is a liability to Holdo's overarching plan.

The time comes and it seems Holdo's agents haven't been successful she ends her life by saving all just like in the movie.

Reason for apparent incompetence solved and Poe learns that there is more than the pulse of immediate battle in a war.

I can't see why nobody brought this up at the treatment level let alone a post-production comic which doesn't address it properly.

Not exactly as bad as pamphlets explaining the black goo from Prometheus bad but not far off.