Pretty clearly the UK government made the agreement in bad faith. The fallback position that it follows if there was no agreed free trade agreement was clearly understood by everyone. It was vociferously emphasised by the DUP in the Commons as the reason they had broken their alliance with the Tories, along with others.

There is no possibility that the government was no fully aware of the implications ofwhat they were signing.

But why should anyone be surprised at an English government acting in bad faith when it sees that as convenient? There's an expression "Albion perfide" which was first used as far back as the 13th century?