A family of Microsoft products that enable users to capture, organize, and reuse notes electronically.
Thank you both for your efforts in trying the troubleshooting steps and for keeping me updated.
I’d like to let you know that Microsoft is currently investigating a known OneNote service incident, OP1454727, which may prevent users from signing in to OneNote on iOS devices. Since this is a service-side issue, no further troubleshooting is needed at this time.
I recommend contacting your school’s IT administrator and asking them to monitor OP1454727 in the Microsoft 365 admin center > Service Health for the latest updates. Microsoft is actively working on a resolution.
Note: In case you do not know who is your IT admin, kindly refer to this article: How do I find my Microsoft 365 admin? - Microsoft Support
Once the issue has been resolved, please update OneNote to the latest version and restart the app if needed.
Also, as many members of the community may not yet be aware of this incident, I hope you find this information helpful. You may consider marking this answer as accepted, as it can help bring greater visibility to the issue and make it easier for others experiencing similar challenges to find relevant information and support.
If you have any questions or need further assistance, please feel free to share them in the comments on this post so I can continue to support you.