There is some confusion about the meaning of 'sovereignty'. What it does not mean is that countries are free to legislate to over ride international law.
I'll leave it to this blogger to express it far better than I can.
At its extreme, this idea of parliamentary sovereignty leaves no constitutional place for domestic courts, let alone international ones (actually, at its most extreme, as noted in my last post and amplified by Ian Dunt’s Substack, it proposes that parliament is sovereign over reality itself).
It is important to understand that these are not arcane points of legal or political theory. They have a crucial practical importance. For one thing, the UK is hardly in a position to call on other states, be it China, Russia or Israel, to act within international law and to respect human rights if its position is that sovereignty allows every country to do whatever it wants. For another, the UK is hardly an attractive partner for other countries to strike deals with, whether about trade or, even, asylum processing, if it reserves the right to violate those deals. And, for a third, which should matter to everyone, this doctrine makes it possible that parliament might act to remove any and every right from any or all of us, with no recourse to any court. It is precisely to constrain that possibility that we need the principle that there are some laws and rights that transcend the power of nation states.
chrisgreybrexitblog.blogspot.com/2023/12/the-brexit-battles-never-went-away-and.html