You can share tags with players of the opposite faction in the open world in the Dragonflight pre-patch. 

Currently, on live servers, whenever a member of the opposite faction tags a mob, it is greyed out for you, and you won’t receive any loot. However, this is changing for the better in the Dragonflight pre-patch. MrGM noticed tags are now shared between all players regardless of faction¬†in the open world.

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