I am not sure if you know the history of this practice.
Theres a label in Los Angeles that has been putting these out for a few years now, Blank City Records. https://www.blankcityrecords.com/
Their releases tend to be post punk related artists.
But regarding the history - this is what was done long ago in order to get forbidden music into the Soviet Union -back in the 40s-50s because the x ray film was easy to smuggle.
the thing about these though - the fidelity is not quite the same as a normal record, and also it should be known that again, due to the material, playing them multiple times quickly degrades the material further, as opposed to an actual vinyl record.
As quoted from one of Blank City Records' owners:
"These “flexis” are constructed from thin, flexible sheets of vinyl composite and are significantly cheaper to make than standard vinyl pressings. You can play them on your turntable, but they also have a limited shelf life —they'll deteriorate and become un-listenable over the course of about 20 plays. “It’s like a Snapchat," Blank City co-founder Marc Sallis says. "You can only play this thing so many times and it’s done.”
What I cant tell by your link is if they are somehow incorporating the x ray film into some sort of clear harder vinyl or if they are just indeed the x ray film flexis
There's a good little documentary on this on youtube: