Is Empty filter is missing

While Exists (or Is Exist - which is grammatically incorrect) is a good filter, Is empty filter is missing - for both standalone filter or router filter. Any known workaround to check if a field that was passed is empty?

Check this - https://forum.pabbly.com/threads/how-to-pass-default-value-in-case-of-blank-response-from-trigger-app.877/

I am using LEN formula to pass the default value but instead of that you can setup a filter that if result of LEN formula is greater than 0 then only go ahead.

I agree, I had first solved it in the trigger.
But what works (now) (for me) is leaving the value empty.