How have they been duplicitous? How about the meetings between Barnier and various Remainers, even though he knew that he could and should only negotiate with the elected government? You mention that their stance has never changed - how then can that be even close to being classed as negotiating. How about telling the UK that they can't cherry-pick the bits they want, then carry in to demand access to UK waters and try to dictate birders in Ireland? There are four years of evidence of EU duplicitousness - but you know all that, don't you!How exactly have they been duplicitous?
As far as I'm aware, they said very clearly in 2016 that Britain would not get a better deal by leaving. They said (also very clearly) that if Britain wanted to keep access to the single market and customs union, then it needed to ensure regulatory alignment. They've kept saying it, all the way through. Their position hasn't changed.
And yet, David Davies, Boris Johnson, Nigel Farage et al all insisted that the EU was going to give us an excellent deal. That of course the German car manufacturers, or Spanish/French fishermen, would all pressure their Governments to give us the deal that the Brexiteers had promised.
Sorry, the only duplicitous types have been the ones who promised you the chocolate fountains and unicorns of a seamless Brexit. It certainly won't be as bad as the doomsayers feared, but it was never going be as good as the politicians promised you.
Take Gove; promising in 2016 that food standards would never, ever, drop, and that British farmers should be happy to vote for Brexit, and that they'd never have to compete with cheaper imports from countries that have lower standards for animal welfare or worse records for food safety. Then in 2020 voting against an amendment to the Agriculture Bill that would have kept him to his word, because obviously his word is good, and the amendment was completely unnecessary...
You are reaching the stage of troll where you are posting not to advance the debate but to stifle it with matters gone over many times. Sooner we are shot of the EU the better - we might then get Remainers actually working for the benefit of this country instead of doing all they can to undermine it.