So many players don't seem to undestand the differecne between an unapproved rubber & an illegal rubber.
Rubbers that are not on the ITTF's LARC are just unapproved rubbers. Rubbers such as super pips (also sometimes referred to as high aspect ratio super long pips) are NOT illegal. They are currently unapproved by the ITTF & so not on the LARC list.
On the other hand spinverted rubbers that are either spoosted or spin glues are "illegal" under the common law. They are only unapproved by the ITTF Rule 2.4.7 but the reason for the Rule for 2.4.7 is what makes them illegal under the common law. This is according to ITTF (not me).
Treated pips are unapproved for use in ITTF events but no because they are illegal like spoosted & spin glued rubbers are.
Of course there are rare cases of pips and anti players spoosting or spin gluing their rubbers . In those rarae cases,yes , it is "iilegal"