Yeah, it has been discussed here (and in many other threads):
It was confirmed that new edits will be working with the upcoming 1.26.1 version of PMS, they will stop automatically changing to “1969-12-31”. But no words if the issue about already edited dates moving backward by one day will be fixed.
This is a huge problem for me too. I modified the date on a lot of music albums, movies and TV shows. And I don’t have a list to find them and correct everything later…