Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
Dear kuaci,
Thanks for sharing updates with us and we really appreciate your effort and your precious time doing those tests.
We've also done a quick test to create list from Excel, change the column type and wait for the next day to see the outcome, however, we cannot reproduce a similar situation on our side.
Considering that issue happens to all Lists that you created and new list saved to Teams Channel got the same error, issue could be related to your account or the tenant background service which need to be checked from the backend.
As forum support, we may not have enough permission and resource to directly check the backend environment.
In this situation, we sincerely recommend you contact your Microsoft 365 administrator, follow steps in this article to create a support ticket with Online Support. The support team over there has higher permission than us, they can remotely help check the situation on your side, involve more resource to collect logs and help you do troubleshoot. This would be a more efficient way in handling this case for you.
For reference: How do I find my Microsoft 365 admin?
Thanks for your understanding and cooperation! Have a good day.
Sincerely,
Rhoda | Microsoft Community Moderator