Specifically this image https://e621.net/posts/2893499 is tagged with "snake_(artist)". The rest of the images under this tag are mine, but this one isn't. It is by someone from Pixiv with the Japanese name "へび" which translates to "snake". How do you usually solve this? My understanding is that the Pixiv artist should get a different tag, but which exactly?

snake-scaly said:
Specifically this image https://e621.net/posts/2893499 is tagged with "snake_(artist)". The rest of the images under this tag are mine, but this one isn't. It is by someone from Pixiv with the Japanese name "へび" which translates to "snake". How do you usually solve this? My understanding is that the Pixiv artist should get a different tag, but which exactly?

For very commonly used names such as this, you'd look at every gallery both artist ls posts to and find their known aliases.
Typically, you will find that the artist would not be allowed to simply have the alias of "snake" and would be required to change it (e.g., snake001, therealsnake, snakearts, etc.).
You would compare these alternate aliases between the two artists and determine the best name they should go by.

In this case, the original snake_(artist) is attributed an artist on FA that had registered that name since 2006. The only other gallery they post to on VCL also have their name set as simply "snake", so finding an alternative name for them is not viable.
On the other hand, the Pixiv artist has a Japanese name that translates to "snake". However, their Twitter handle and Pawoo account go by a different name called "jack hound". You would take this alternative name and make it their main alias, see jack_hound.

In very extreme cases, where there are simply no other alternative names, you can resort to calling them via the year they registered their accounts, (e.g., snake_(2007)), by where they mainly post to (e.g., snake_(fa), snake_(pixiv), or any unique identifiers linked to their account (e.g., snake_(pixiv_275699)).

thegreatwolfgang said:
You would take this alternative name and make it their main alias, see jack_hound.

Thank you, I see you've already done that.

I guess I should link my account to my artist tag.

snake-scaly said:
Thank you, I see you've already done that.

I guess I should link my account to my artist tag.

Somebody else did it for you, but just did not mention it here.