see
Repair project items—ArcGIS Pro | Documentation
there is something to check...
Required connections in an ArcGIS Pro project—specifically, the default geodatabase and default toolbox connections—are not allowed to become invalid. A project’s default geodatabase or toolbox should not be deleted, moved, or renamed. However, if this happens, new default items are created and added to the project. The invalid items still appear in the project and can be repaired but are no longer the default items.
so if you see a new project toolbox, in catalog, then something may have happened along the way. Also, make sure names are unique (toolboxes, tools, etc)
... sort of retired...