BTW as to why I think this about the order of the properties in the services definition and the Symfony parser: I went through all the services in all the modules in core and close to 200 contrib modules, and almost all of them have arguments before tags. The few that didn't were either cache services, drush, or from modules that would rarely or never have their services loaded on the site I'm seeing the issue. That would explain why I only see the issue with this module.
Patch that reverses the order of tags and arguments in views_show_more.services.yml
sethfisher → created an issue.
Here's a new version of the patch which fixes an issue I found. If you edit an existing node with a pre-existing value in the target field, choosing the triggering value will set the target field to the pre-existing value rather than the value that's supposed to be triggered.
This patch works for me