[Meta] Big Pipe related issues, causing seemingly random failures

Problem/Motivation

This issue is intended as a resource, listing Big Pipe related issues, causing seemingly random failures, affecting contrib modules and Drupal core.

Inspired by #2829040: [meta] Known intermittent, random, and environment-specific test failures, Big Pipe can sometimes cause mysterious bugs, like certain JavaScripts not loading, or loading in the wrong order. It can be difficult to pinpoint the problem, so perhaps a [meta] issue collecting them can become a resource, and help users looking for a cause and solution?

Steps to reproduce

See a bug, spend some time understanding it, realize it is Big Pipe related.

Proposed resolution

Collect issues, and expand this issue with descriptions of different scenarios, and solutions, to become a resource and help, guiding users to faster understand the cause, and solution to their problem.

Maybe creating a "How Big Pipe can cause mysterious bugs" documentation page in the style of How to fix "The following module is missing from the file system..." warning messages is better?

Remaining tasks

User interface changes

Introduced terminology

API changes

Data model changes

Release notes snippet