Musings about a United Ireland have certainly been going on since the brexit vote, not just now since the Northern Ireland Protocol was dreamed up.
It looks to be like a diversion by brexit supporters as a desperate attempt to say 'See. When I voted leave I was secretly doing everybody a favour by actually voting that way as a sneaky route to a United Ireland'.
The brexit vote was to leave. Leave means a border between two different systems. How to manage and run that land border in Ireland remains, as it has been since the vote, the problem.