On this picture contributed to Google Maps in December 2020 we can we read the sign saying spots 5,6,7 are for charging and max 2h blue disc, whereas the rest of the parking is paid.
On the Chargemap pictures from 2018 the same sign seems to be already present. We can also read the same sign on the Google Street View images from July 2024. On the &Charge contributions from 2025 we see a sign in the background that seems to also still be the same.