Punched tin on a antique is rusted.

You could try using steel wool on the tin to buff the rust off. Just be gentle and test a small area first.

This site offers step by step ins like an old toothbrush, toothpicks, car wax and steel wool. Good luck! https://www.doityourself.com/stry/how-to-clean-antique-punched-tin

This is for a tin box, but it is a different method than I've ever seen. She finishes with a potato and salt. If the ideas you don't have yet don't work or you don't want to use steel wool, give this one a try.

http://www.athriftymrs.com/2009/10/how-to-clean-a-vintage-tin.html

Try rubbing mineral oil on the rusted areas. Use a soft cloth. Keep rubbing until the rust is all gone.

If it isn't painted Bartenders Helper is something to try. It is a light abrasive and helps with lots of household jobs.