Syntax structure
The current syntax for the /scoreboard players tag command is
/scoreboard players tag <player> <add|remove|list> <tagName> [dataTag]However this is incorrect (also because of MC-80856) because the list option does not operate with a dataTag.
Maybe something like this would be more correct
/scoreboard players tag <player> add <dataName> [dataTag]|remove <dataName> [dataTag]|list
You meant to comment on WEB-90, didn't you?