Up to 2024, the data is from the MN survey, so it makes sense that there are a lot of 'dont knows' because users are answering a general survey and maybe havent thought about it, or dont want to say.
Since 2024 the data is from politics tracker survey. I dont know if it is significant, but it could have attracted people who are politically engaged, therefore the 'dont knows' fell. Or it could have been that the survey was carried out nearer to an election?
The last survey was august/September 2025, was that before the greens gained popularity?