Compare with surrendering the sovereignty of a nation.
What does, or might, "sovereignty" mean in practice?
The ability to defend its citizens/subjects against external aggressors sounds like a good starting point. But if the Argentinians become argie again and re-invade the Falklands, we will have to beg the French to lend us their aircraft carrier. Not much sovereignty there
The ability to keep the electricity flowing is another good starting point. But we are currently begging the French to build a vitally needed nuke reactor, and the Chinese to lend us the money to pay for it. Not much sovereignty there
And there are many other similar examples which indicate that sovereignty is an outdated concept w.r.t. the UK and many other countries.
So it sounds like "sovereignty" is a
feature not a
benefit - and that its loss has nothing to do with the EU.