See MBS-10193. It'd be a massive undertaking to correct all the links in the database.

I specified that this only affect album links for a reason: Since the redesign that went live on April 17, Apple Music artist URLs only show content available in a viewer's region, based on their IP address. The only way to ascertain the availability of content not available in one's location is to preview it through an old iTunes artist URL (swapping out the TLD as needed). From there, the album links can be copied and pasted into https://etc.marlonob.info/atisket/ to import them into MB.

Update: As of this writing (2021-03-25; it may have been implemented earlier) old iTunes format artist links automatically redirect to the Apple Music web player. It is still possible to view content from specific regions by swapping the TLD in the URL, so I think it's high time we retire the whole iTunes link format.