This could be a case of enforcement against large companies taking longer to conduct, given the complex nature of the cases and the resources of the legal teams involved. My understanding is that a lot of stuff is pending before the Irish data protection agency.
That certainly plays a role, especially as soon as courts get involved (or will get involved), see e.g. the pre-GDPR cases against Facebook still bouncing around the Irish court system. Smaller cases can be handled without international coordination, the facts are often easy to determine, ..., which makes them faster to process.
And the rules about international coordination mean other countries have to wait for Ireland in many cases.
