Redirecting instead of rewrite

[dt-humaan]

We have 2 sites hosted within vercel using next.js and a monorepo

next.config has rewrites setup

rewrites: () => {
		const rewrites = [];
		if (process.env.NEXT_PUBLIC_SITE === "sitea") {
			rewrites.push({
				source: "/siteb{/}?",
				destination: "https://siteb.vercel.app",
			});
			rewrites.push({
				source: "/siteb/:path*",
				destination: "https://siteb.vercel.app/:path*",
			});
			rewrites.push({
				source: "/testing{/}?",
				destination: `https://example.com/`,
			});
		}
		
		return {
			beforeFiles: rewrites,
		}
	},

This was all working as expected
user visits https://example.com/ and sees sitea
user visits https://example.com/siteb/ and sees siteb without being redirected

recently however if
user visits https://example.com/siteb/ they are being 308 redirected to https://siteb.vercel.app/ which is not the intended behaviour

for testing i’ve added another rewrite to a url not hosted on vercel and can see that working as expected.

[amyegan]

Thanks for reporting this. Our engineering team is currently investigating.

It looks like you also have a support case open with our customer success team. They’ll share updates there as soon as new details are available.