Is it still required to use the contrib module image_url_formatter to be able to link an image in a post to a file on the site?
I saw this forum post https://forum.backdropcms.org/forum/link-image-field-link-field-entity from a few years ago and also the core issue it linked to at https://github.com/backdrop/backdrop-issues/issues/2921 which still looks to be unresolved.
OK, off to check that module.
I figured it out! Had to do some fiddling with css to make it work but it looks fine now. In my theme, there was link styling like this:
So I added this exception for text within paragraphs (<p> tags):
Doesn't appear to have broken anything else.