Blender is developing intensively and new versions of the program are released quite quickly. In this case, compatibility often suffers – when we open a project created in earlier versions of Blender, it can be opened not correctly. Sometimes this happens because Blender stores all user interface (UI) settings and options in every .blend file. Opening a project with the Load UI option unchecked can help.
In this case, Blender only loads the project itself, without any UI settings that may have changed in the current version.
Pressing the “Purge” button cleans the current open scene – removes all unused objects from it (mesh, nodes, materials, textures, etc.). However, this button is located very inconveniently, in the Outliner header and is visible only in the “Orphan Data” Outliner mode. For quick access to this button we can move it to the header of the 3D Viewport.