Tl:dr, turns out in most markets Pyrex switched off borosilicate glass, which is toxic & expensive to dispose of. And now uses tempered soda-lime glass, which i

Tl:dr, turns out in most markets Pyrex switched off borosilicate glass, which is toxic & expensive to dispose of. And now uses tempered soda-lime glass, which is more succeptible to thermal shock breakage but still pretty ok. PYREX all caps is supposed to mean the classic borosilicate. Lowercase is likely soda-lime. Corning owns & licenses Pyrex trademark.