im currently working on some more e2e for streaming. during working on that i found out that enabling streaming in pages-router will break this:

it turns out that the headers is incorrect. the body is actually correct, but the headers from the response is not what it should be. same thing happens if i add the test to app-router aswell (which already has streaming enabled)

here is a reproduction of the problem. it seems to work with local build, but not once deployed to AWS. steps to reproduce:

# this will deploy to AWS with SST
pnpm install
pnpm sst:deploy

# i added a local opennext build that seems to work fine
pnpm opennextlocalbuild
# then visit http://localhost:3000/external-on-image
# however it seems that http://localhost:3000/opennextjs is broken locally. i guess its also related to headers

then go visit the /external-on-image, /opennextjs and /rewrite. they are all external rewrites. there is also a massive amount of headers on the response, so something with the headers is broken.