Brexit was sold as being protectionist, but it was actually the opposite. We gave up huge amounts of sovereignty.
For example, we used to control both sides of our border with France, but Brexit gave up control of the French side and sure enough the boats started coming. The French are not all that interested in policing our border for us, beyond what they can get out of any deals they made with us.
On rule making too, we are now pretty much obliged to accept whatever the EU does, because we are too small to make big demands of our own. Every time we diverge from what the EU does, it damages our economy even more. Farming is a good example. Brexit was supposed to help our farmers, but it's shafted them with extra red tape and costs when they want to export. Some naive fantasists thought we would become self sufficient and eat British grown food, but it's not really to our tastes and many can't afford the price rises that would come with it.
So don't worry, the next protectionist will argue that Brexit wasn't done right and their version will somehow not be a total disaster.