Groupe de produits et technologies Microsoft utilisés pour le partage et la gestion du contenu, des connaissances et des applications.
Dear respected YANNICK FAUCHER1,
Good day! Thank you for posting to Microsoft Community. We are happy to help you.
I’m sorry you’re having a problem and for the situation you encountered, we deeply understand the inconvenience caused and apologize for it.
As per your description, based on my test, it seems that I can confirm I also meet the same behaviour as like you described above. In SharePoint Lists UI "Open details pane" icon is missing.
Since all SharePoint list get the same behaviour and new created as well. I'm afraid this issue could be a temporarily server-side issue which needs to be investigated via remote section and collect logs and fixed from back end.
I would suggest you raise a support ticket from the Microsoft 365 admin center and report the issue to the related team. The more reports they receive from different customers, the more likely they will be able to find something affects users in common, do investigation and fix it soon.
Reference: Get support - Microsoft 365 admin | Microsoft Learn
Note: To create a support ticket, you need to have Microsoft 365 admin privileges and if you aren’t admin of your Office 365 organization, please contact the admin of creating a new ticket.
Reference: How do I find my Microsoft 365 admin? - Microsoft Support
Please accept my Apologies and I do feel regret for not resolving the problem and redirecting you to the related development team but the fix to your concern can be find out through the HAR logs and suggest you raise a support ticket from the Office 365 admin center, where the related team will investigate the problem further by collecting the HAR logs.
I'm sorry and I apologize for that.
Temporary workaround:
The workaround is to click on the 'More Actions' ellipsis (...) > Details.
Appreciate your patience and understanding and thank you for your time and cooperation.
Sincerely,
Waqas Muhammad