Date picker is not displayed at first load in edit mode

Tested on XWiki cloud 12.10.6 and local instance 12.10.8.
This issue can be reproduced constantly on Chrome (version 91), and is not always reproducible on Firefox (version 89)

To reproduce:

• Install blog extension
• Create a new blog post
• Click on the date picker field
• The datepicker doesn't appear as expected, without any error in the console
• To make the datepicker appear, you need to refresh the page in edit mode.

Seems similar to XWIKI-17988