@Nikerabbit - thanks for letting me know about this. It would be easy to change the code to use "HtmlPageLinkRendererEnd" instead of "LinkEnd", but then Page Forms would no longer support MediaWiki versions below 1.28 (notably 1.27, the current LTS version). I could have both hooks, but it wouldn't be good for both to be called. Is there some easy way to check for the existence of the "HtmlPageLinkRendererEnd" hook, so that the function called by "LinkEnd" can exit out right away if the other hook exists?

As far as I know the only option at this case is to do version_compare against $wgVersion.

Looking at https://gerrit.wikimedia.org/r/c/mediawiki/core/+/284750 you could also do class_exists( 'LinkRenderer' ) which was added in the same commit.

@Yaron_Koren Are you planning a new release anytime soon that would include this fix?

Yes - Page Forms 4.4, which I'm planning to coincide with the end of the Google Summer of Code, because a big part of the new version will be a current GSoC project.