There are a lot of artist tags that also use "(artist)" alongside the artist's name. This is mostly done to distinguish the artist from anything else, such as flag) and flygon, but then there are others, like pinkthehedgehog) and bizymouse, who have the (artist) tag despite having names that couldn't be confused for anyone or anything else. I'm wondering if there's some sort of standard for inserting (artist) into artist tags.

Usually just to distinguish between commonly usable words and the suffix it has. (Artist), (character), (species), and (copyright) are all for such, but they all also immediately make the text given into the category the suffix is called.

I try to tell people to avoid using suffixes until needed, it is a waste of typing if you have an original name or etc., but those suffixes are needed if it is shared with another thing, or optional, but useful, if the name can be mistaken as another thing.

When stuff like your listed happens, I assume it is because people are lazy and don't know how to make categorized tags. It should be fixed if isolated, but I've noticed it go too far and would make changing the tags hard if you don't use tag scripts.

Artists often have a character with the same name.
So when the first pic by the artist "cuddlebear" gets posted, it will have the tag artist:cuddlebear
But then someone posts a pic by the artist "snugglewolf" that contains the character "cuddlebear", and it gets tagged
character:cuddlebear
(which changes the type of the "cuddlebear" tag)

People *should* know that artist tags have priority over character tags, so the right thing to do is to use:
artist:cuddlebear
character:cuddlebear_(character)
But many don't, so it is useful to always add _(artist) to artist tags.

Maybe e621 should warn you if you try to change the type of an existing tag.

Either that, or e621 should allow the same tag to exist multiple times, with different types.
So a post could have all of these tags:
artist:cuddlebear
character:cuddlebear
copyright:cuddlebear

Searching for "cuddlebear" would find all three tags.
If you're only interested in the artist tag, you would search for:
artist:cuddlebear

Occasionally an FA user known for their sona will draw something of their own, making char:cuddlebear (100 posts) the default tag and cuddlebear_(artist) (1 post) a useful tag despite the proposed priority system. I wish I could give an example but I don't recall where I've seen this...

This reminded me of that_flower_what_appears_in_your_lawn_but_nobody_gives_a_single_fuck_of_her_(character).

Yes, that definitely needed the *_(character) disambiguation.

But seriously, there's no need to add those to unique names. And it's often safe to remove them from newly created tags; most are made by new users who haven't yet figured out how to set categories properly.

Genjar said:
This reminded me of that_flower_what_appears_in_your_lawn_but_nobody_gives_a_single_fuck_of_her_(character).

...Just out of curiosity, is that a character from a game or comic or something?