Philippines is specifically listed on the country allowed to play on this casino so maybe they are licensed by PAGCOR. I tried to browse the PAGCOR website for the list of regulated casino but their website is so crappy that makes it hard to browse.

Here’s the list of Gamba allowed country:

Canada, Japan, South Korea, Brazil, Argentina, Chile, Mexico, South Africa, New Zealand, Malaysia, Philippines, Vietnam, Colombia, and many others.

https://help.gamba.com/en/articles/8271491-geo-restrictions-and-licensed-operation