I mean, it's just a literal non-event legally. I'm repeating myself here, but OpenAI already operates in the EU. EU users can already use ChatGPT, with some assurances about adhering to GDPR. Offering the ad-free tier to a subset of EU users for free, who could already use the tier with ads for free, doesn't change anything legally in regards to data processing.

If you want my commentary on the political context, obviously I think it's not very intelligent for nations to be trusting a US corporation with all of their citizens' data. I think the most impactful use of LLMs is going to be their usage as surveillance and propaganda tools, so this is probably not a prudent decision. But legally, as pertains to GDPR, this is not different from the status quo in any way.