Can multiple people edit the same feature class, in the same file geodatabase, in different projects, at the same time?
Is this a new feature of ArcPro?
How do we disable it?
See the Help topic: File geodatabases and locking. It is my understanding that lock files should be preventing this.
Compressing a file geodatabase makes it read-only. Once compressed, a feature class or table is read-only and cannot be edited.
From the Types of geodatbases Help:
File geodatabases are designed to be edited by a single user and do not support geodatabase versioning. With a file geodatabase, it is possible to have more than one editor editing at the same time provided they are editing in different feature datasets, stand-alone feature classes, or tables.