You said You bought a 50 spindle, Your link goes to a 25 spindle.
I never heard of PHILIPR04 in Sony spindles before, but nothing is impossible.
Because Sony cooperates with the manufacturer MBI in India and labels MBI R06, sold as Sony BD-R25 6x.
MBI also manufactures BD-R25 4x with the mediacode PHILIPR04, so why not.
The linked seller is a well known and experienced ebay seller, I donÂ´t think he sells fakes deliberately.
Does the spindle have an original Sony banderole/shrink wrap?
If not, maybe the seller made a mistake when repacking the discs, but I donÂ´t think so.
If it has a shrink wrap and You find the signs ã‚¤ãƒ³ãƒ‰è£½ on it, it means Made in India and I would say Your discs are "genuine" Sonys from a "new" manufacturer not known before for making BD-R25 4x for them.
The mediacode PHILIPR04 is mostly notorious for cheap and crappy labels, but it can also be decent.