Problem/Motivation
The oEmbed system requires all non-link resources (i.e., photos, videos, rich text) to have an explicit, non-zero width and a height defined, and throws exceptions (in \Drupal\media\OEmbed\Resource::__construct()) if they don't. This is in keeping with the oEmbed specification. However, some oEmbed providers, like Twitter and Instagram, disobey this rule because the assets they serve contain live text, and may be responsive, so they can't really have a known, predefined height. Therefore, they will be incompatible with our oEmbed implementation.
Proposed resolution
Loosen our adherence to the oEmbed standard in order to support remote assets with dynamic heights.
Remaining tasks
Figure out the best approach, write a patch with tests, and commit it.
User interface changes
None.
API changes
None, really. The oEmbed resource value object will become a slightly more permissive, but I'm not sure this qualifies as an API change.
Data model changes
Likely none.