One way is to disable automatic trailing slash redirection https://nextjs.org/docs/app/api-reference/next-config-js/trailingSlash and then do it manually via routing middleware https://nextjs.org/docs/app/building-your-application/routing/middleware

why do you want it to be 301 tho?

308 is better in basically every way (ie if method is POST it stays post instead of turning into GET)

I'm sorry, I just saw your response,
My seo team thinks 301 is friendly

I'm going to try to customize the handling of tail slashes in the middleware,thanks you!

Well you can tell them to do some more research as google and others treat them the same (as long as both permeant) - I think it's just 301 is more known and talked about

Yes! I will keep in touch with my seo team on the selection of 301 and 308.
Thank you very much. I have two options. I feel like I can go in and go out,lol

301 is friendly compared to 302 (tells google to transfer juice from one url to the other, being permanent.) 308 and 307 are the better counter part, as @riský is advising you. so yeah push against that request because the year is 2024