This says nothing about the Giro.The whole Giro d'Italia field looks sub-par by now. Not just Bernal, but also Vlasov who's an also-ran in this Vuelta a Espana so far!
I wouldn't blame it on Covid-19, but on Bernal not being as good so far. Right now it looks as if he clearly benefited from a mediocre field and a strong team to the jersey. Additionally the route was quite weak by Giro d'Italia standards as well.
Sometimes a guy is just in worse form in the Vuelta than in the Giro.
Bernal was very strong in the first 2 weeks of the Giro. He was a bit lucky his main opponents in the Giro were also a bit inconsistent.