This query variable is not public

Like this post: https://ww.wp.xz.cn/support/topic/plugin-monkeyman-rewrite-analyzer-this-query-variable-is-not-public-and-will-not-be-saved?replies=2

We’d like to know what it means to have GET parameters crossed with a red bar, we didn’t understand the other person’s comment.

Here is a screenshot of what we seee and tested.
https://magikweb.ca/download/hotlink/rewriting.png

Thank you!

https://ww.wp.xz.cn/plugins/monkeyman-rewrite-analyzer/