Covid and Brexit both contributed massively to the housing problems everywhere, most especially in Cornwall, but even 'upcountry' where I live, since I am on the wrong side of the Tamar in South Devon. Which, incidentally, is mostly dependent on the tourist industry too and has suffered in similar ways. And despite there being a little more prosperity here, there is still a huge disparity between the wealthy landowners, the second home owners, and the local population drawing low salaries, and there is a major shortage of affordable residential rental properties.
I will say, although I have a great deal of sympathy for the Cornish, what the hell were they doing voting to leave the EU? They voted out and then started asking for assurances that the funding promised by the EU would still be forthcoming. Umm...wrong order guys. Cornwall lost a lot through Brexit and they only contributed to that.