PS2 won't read DVDs/PS2 originals but reads DVD-Rs and CDs

Hi all. As the title says, I'm a little confused as to why my PS2 won't read my PS2 originals. It was previously modded but after some issues with the modchip, it was removed. If I were honest, I didn't own any PS2 games before getting my PS2 since it was one of those consoles that I messed around with between playing on PS3 but after since having the modchip removed, I bought the 3 games that I play most of all but my PS2 won't read them at all. 2 of the games have perfect discs and one of them was brand new but my PS2 won't read any of them. I just put in the disc, it tries to read it for a while, then nothing happens, I just get taken back to the browser screen. I tried one of my DVD films in it, same problem. It does read Audio CDs and seems to have no issues actually reading a DVD-R backup (though I get the red screen ofcourse because it's not an original game) so I'm a bit confused.

I checked the bottom of my PS2 and it is a PAL console (SCPH-90004) and the games I bought are PAL so region-wise, it doesn't make much sense, unless it's an NTSC console in a PAL shell? If that is the case, what are the symptoms associated with trying to load an import game into an unmodded PS2? Thanks.