I'm working on a project where we can't use public storage at all - it's S3 / CDN storage or nothing at all. Drupal core currently requires public files, but with the other work going on we're making good progress towards eliminating public storage.
However, since it's still a requirement, it's entirely possible for core or contrib code to hardcode public:// URIs. Drupal 7 modules offered stream wrappers that altered out the public wrapper, but they were fragile and had performance problems with code that assumed public streams were equivalent to local disk.
Our thought is to start by altering the public wrapper, but to not actually redirect to a scheme and to just log when it's used. Later, we would add an option to throw hard exceptions when using the public wrapper. Or perhaps even support redirecting to a flysystem adapter, being sure to document the performance and stability issues with it.
Postponed
3.0
Code
Not all content is available!
It's likely this issue predates Contrib.social: some issue and comment data are missing.