There a re refinishers for nickel I would start there .

Would you please that and there process?

Here's a video on a how-to, it's easy.

https://www.youtube.com/watch?v=VkeUKT-Go3Q

And some steps below: (who ever cleans, make sure not to use any chemicals. u want a cleaner made for metal only)

Steps to Refinish a Hammered Nickel Sink

1. Deep Clean: Remove grime and soap scum using warm water, a mild detergent, and a soft cloth or a blue Scotch-Brite pad. For stubborn stains, use a 1:1 mixture of white vinegar and water.
2. Remove Tarnish/Polish: Use a gentle copper or metal cleaner, such as Wright’s Copper Cream, to remove spots and bring back the shine.
3. Apply Protective Wax: To protect the finish and slow down the natural aging process (patina), apply a high-quality wax, such as Flitz Wax or a specialized sink wax, using a soft cloth.
4. Buff: Once the wax has dried to a haze, buff it to a shine with a clean, dry microfiber cloth.

Maintenance Tips

• Prevent Water Spots: Dry the sink after every use to prevent water spots and discoloration.
• Avoid Harsh Chemicals: Never use cleaners with acidic, alcohol, or abrasive agents.
• Reapply Wax: To maintain the finish, reapply wax roughly every four week

Thanks Beth.

It appears to have a topical coating like lacquer that has been removed in some areas. You'll probably have to remove it all and go from there.

Thank you Beth and everyone