"A lack of data sovereignty options was another reason that respondents gave for ditching cloud providers, with European privacy law the GDPR cited as a prime example, but there are a growing number of requirements worldwide for data to remain in a particular country, according to IDC."
The fact that no matter where you put your data, whether it be in your own country or within the EU, you are still at risk of it being transferred to the US due to the cloud act, you can not use an American cloud provider if you want to be GDPR compliant. Hence the rulings in a few EU countries so far (with the others having cases pending).
So as long as there is GDPR and the Cloud Act, either all EU companies have to stay away from the American cloud providers, or the Cloud Act needs to go, or these America companies need to completely split the EU and rest of the world operations into complete distinct entities so they do not fall under the cloud act.