I'm not surprised. This was one of the aspects of Brexit that seemed completely untenable and disastrous. Some aspects of Brexit are "bad but acceptable" but this was an "if we don't revert this one British R&D and science are screwed" aspect
the EU delayed implementation in order to use horizon as a stick to apply political pressure in an unrelated area (as it continues to do with switzerland)
so I'm not sure that reality reflects your point
that's an easy one, remaining in the EU