I believe this was the Schrems 2 case from 2020 that declared that the EU US Privacy Shield was insufficient at guaranteeing the privacy of EU citizens due to the CLOUD act, which would require US companies work with the government to potentially spy on EU citizens.
I’m not sure what has happened since then or the legal status of this issue.
The US under Biden did something that made it valid again and then the US under Trump made it invalid again. Right now it's illegal for an EU company to store unencrypted personal data with any US company.