Next.js missing `http.client` spans / fetch instrumentation issues

[mydea]

Description

We have seen cases where the http.client spans are missing on pageload transactions in Next 14 with app router: https://test-cgomez.sentry.io/explore/traces/trace/f58bd4d77ebf488683b44146597ded54/?node=txn-17dc2947119745a585b6205da5c8adde&project=4507645526868048&source=traces&statsPeriod=1h&targetId=fbe2d8afbdd7a34e&timestamp=1748011122

(Clarification on this: http.server spans that happen after the pageload is done should be siblings of the pageload, so in the same trace, but not children of the pageload - this part is correct. What is weird is having http.server spans as direct children of the pageload without a http.client span in between, basically. Anything that happens via http or fetch should have an http.client span in-between, can't really imagine something else is making this request there...?

Then there has been an issue where a SSR fetch call (on the server side) is not showing up in the http.server transaction but standalone, somehow some link is lost there somewhere: https://peated.sentry.io/explore/discover/trace/436a8df987bd463b892b2bfb01954062/