No one went to jail: https://noyb.eu/en/where-did-all-reject-buttons-come
If not, then the 1st step to jailing people is to change the law.
The EU did find that IAB (behind one of the "industry standard banners") was liable for fines: https://www.euractiv.com/news/top-eu-court-finds-widely-empl... But unfortunately that was partly dismissed on procedural grounds and went nowhere: https://techgdpr.com/blog/data-protection-digest-19052025-di...