It's actually a 31-character limit (buffer is size 32, including the terminating NUL character).
Aliases can go to 64 characters, but the name must still be < 32.
Note that the above was from before 10.8, so it depends on the release level of the
Here is the information on naming limits: https://pro.arcgis.com/en/pro-app/help/data/geodatabases/manage-sql-server/enterprise-geodatabase-li...
The length does not look like an issue.
Is there another ArcGIS client (Desktop / Server / Enterprise / etc.) connected to that table?
Are there any other locks on the table?