This change is in the endwalker patch notes and kind of blows for players like me. I play every job and spend my free time joining party finders for people learning savage and help them learn. With this change, I won't be able to see parties that I could join on a different job. Leaving it as is won't hurt anything, but changing it will make it harder for me to find these parties looking for help, as I'll have to change jobs many different times if they're almost full.
They're not going to hide [One Player Per Job] parties that are for your current job. They're going to hide [One Player Per Job] parties that already contain all of the jobs your Search Criteria say you're willing to play. If you have every job you're willing to play selected you will still see parties that have [One Player Per Job] if any one of those jobs is still available. This isn't changing anything in the way you think it's changing, and it's not going to make it harder for you to find a party.
This will hide any [One Player Per Job] party that includes a red mage:
https://i.imgur.com/JoRBUer.png
This will show [One Player Per Job] parties even if I am a red mage and there is already a red mage in the party:
https://i.imgur.com/3kOrdf8.png
I think this is a good change. It's pretty annoying to select "only show me PFs I am eligible to join on my current job" and then, oops, can't join even though it's showing me the listing.