Re 1. This is expected behavior. Starting from 1.7.18 the calendar widget is a native widget, so it now opens a default card for a record, that can be customized and can show additional fields that weren’t available before. You can learn more about default record card here Record cards - Grist Help Center
Re 2. This is a new issue, not sure yet what is the cause of it. Can you maybe share a sample document or tell me what is your timezone and locals setting detected by Grist. You can see it in Document settings page Document settings - Grist Help Center .
I didn’t notice the news about the calendar, thanks so far.
Below you can see a screenshot that shows the problem on 31.10.2026. I´ve seen, that on some other days it works well. I’m using GMT +2 as timezone. Unfortunatly I´m not allowed to upload the grist-file, because I´m a new user. If you need it, tell me how I can upload.