This is probably in link with the hue emulation binding. Are you sure that you are or were not using this IO service?
I am not emough aware of hue emulation service to explain what is the need of this tag.
OK, I use the HUE Binding and I guess this includes the HUE Emulation. I would understand if the all HUE devices has the tag but why every device (or better most of all) ? I think it has no impact regarding the performance but I will remove it step by step. It could be aso that it was a bug in an older version and now visible.
The hue emulation has tagged items with the HUEEMU metadata for a very long time and the only difference in OH 4.0 is that this is now visible in the UI.
If you have items tagged with HUEEMU then you must have the Hue Emulation addon installed or previously had it installed. If you are actually relying on the hue emulation then removing that metadata will break it.
@AndrewFG Yes, this is what I understood too. @Lolodomo I add with a slash the emulation in the header of this topic. I have not installed the HUE Emulation binding actual but I can’t say if it was installed in a previous version. @MikeJMajor I never have tagged any item with HUEEMU - thats the reason why I wondering - this must be done automatically and is now visible. I would understand that this tag is assigned to items which are relvant for the HUE Emulation but not for every item.