this is exactly why the "muh sovereignty" argument is so stupid as a criticism of the EU.

there's sovereignty on paper and sovereignty in reality,, the UK and switzerland as well as the rest of europe lost their "real" sovereignty long before the EU was formed, the only nations that have any actual sovereignty are countries that are regional powerplayers like unfortunately china, russia, turkey etc. (and ofc the US). The EU is just an attempt to create a power bloc that is able to exercise sovereignty out of nations that approximately can be counted on to have common interests - it's a way to lean on each other to maintain our sovereignty, not a subersion of our sovereignties. This means often that the common good must override national interests too which is where the nationalist voice comes from (other than russian propaganda ofc)