Say you are using a plugin that sends tracking requests like Form Analytics.
If you disable this plugin, then the tracking code containing Form Analytics may still be cached in some browsers and these clients keep sending form tracking requests. Because the plugin is disabled, no action it would be found to handle this tracking request so it would fall back to tracking a page view even though it isn't a page view. This could result for example in actions being tracked with no action title but the URL where it happened. Of course it would result in more page views.
I suppose there be two ways to fix it:
action_nametracking URL parameter is set. Downside: Breaking change if someone doesn't send this parameter. Would need to be solved as part of some major release.
We went with option three, a new request parameter.
Documented in https://developer.matomo.org/api-reference/tracking-api we added a new HTTP Tracking parameter
ca basically stands for custom action.