With iOS 14 or later iPhone owners can display widgets on their Home screen to access their favorite information quickly. While this is a great feature that allows users to customize their devices, there seems to be a bug with some iPhone owner's Calendar widget. Some widgets are getting stuck on a certain date and won't update. There also doesn't seem to be a fix for this issue at this time.
You can try removing the widget and reinstalling it on your Home screen:Remove Widget
- Touch and hold the widget that you want to remove.
- Tap Remove Widget.
- Tap Remove again to confirm.
Hopefully Apple will offer a fix the bug in a future update, but for now there doesn't seem to be an answer to this problem.