The topic of whether data and media have become singular mass nouns is one of the topics people get very angry about in these discussions.
I would like to say that I can see the sense of data being/becoming a singular noun in general usage. After all, we don’t usually use the singular datum in general English.
Nevertheless, it is still the case that legal texts prefer the plural.
Translators unfortunately have to think about these things.
It has come to my knowledge that while the GDPR uses the plural, the English Data Protection Act 2018 uses the singular.
The ICO seems to use the singular too.
Pam Peters (Cambridge Guide to English Usage) says it can currently be either singular or plural, that in about 80% of cases it is indeterminate (e.g. ‘data collection’ – no verb indicating number), and that many writers try to preserve the plural by claiming that the singular is ‘only spoken usage’, ‘only American’ (!), ‘only technical texts’ and all sorts of things.