Greyed out text not making intuitive sense

This may seem like a silly question, but I will ask anyway. When I bring up a table and display it's data, all of the "null" content is greyed out. Makes sense. When I start to filter the data some additional data gets greyed out, but I cannot make sense of the reasoning? I can for instance put in "2667" in the filter and it subsets the rows with 2667 somewhere in any field, but other fields in other columns sometimes have black text and sometimes greyed out text even with the same values. For instance one row has "CD" in a column in black text and the following row has "CD" (same content) in grey text. Note neither match in any way the filter content of "2667". The fields matching the filter content ARE highlighted in beige/yellow properly. What is the greyed out text "trying" to tell me I cannot intuit?

Version 6.5.7 is the one I am using now.

Here are 3 examples with lots of gray text and some columns having same vales in multiple rows, some gray and some not.

too large - here are the others.

Hmm... Ok.... Did not know it was something that was broken - just made no sense to me. Guess I am glad I reported it after pondering for about a year...