Yep. It's actually old, even before they adjusted the 9-dash line. Originally, it was the KMT who disputed it (and when they fled to Taiwan, Taiwan later continued the dispute, usually when the KMT was in power).
I think the last time I heard about it was in the early 90s, in school.
In any case, PRC-CCP reviving this dispute was strategic. And the Philippines really need to be very careful to avoid any mistakes.
This year is very dangerous for the region.