That’s correct. It ignores the history of those cards completely – both their past reviews and any future reviews. But it’s a really extreme solution to a limited set of issues, and I don’t think it’s necessarily a good fit for you.
It sounds like you’re talking about the natural evolution/variation of grading habits – as opposed to a pattern and practice of clearly erroneous grades. What you describe is already handled in most cases by the optimizer, which gives more emphasis to more recent grading history (i.e. the way you grade cards now). Unless you have a specific issue with your parameters and scheduling that you’re trying to overcome, I don’t think you should set an ignore-before date.
The short answer is: Yes, those cards will be scheduled by FSRS too, even though they are excluded from optimization.
That has been seen a couple of times, but I think it will turn out to be more of a display issue than anything else. Your narrow/portrait screen is especially confusing, because it doesn’t show you the column with the history of recorded Difficulty values (which you’d see in landscape), so the card looks untouched by FSRS.
I expect that current DSR values will be recalculated and displayed again the next time they are needed – after re-optimization (if it includes those cards), or before the card is studied/scheduled/re-scheduled.
See also: this recent comment on Reddit from MohammadAzad [@ZornHadNoChoice , this is you, right?] about what else does/does not fix it.