The search filters when: and date: don't act the same

Bug
1

If you want to browse or search via date. It seems that When tag is way more restrictive than Date

This works
http://localhost:1787/tag/When/2021/4
http://localhost:1787/search?q=When%3A2021%2F4
http://localhost:1787/search?q=date%3A2021%2F04
http://localhost:1787/search?q=date%3A2021%2F04%2F17

This doesn’t work
http://localhost:1787/tag/When/2021/04
http://localhost:1787/search?q=When%3A2021%2F04
http://localhost:1787/tag/When/2021/4/17