Not sure about Singapore but Malaysia's racism is not complicated. It is discrimination into law. It makes things rather clear. About discourse of course there is not discussion to have.

a major factor is the lack of societal assimilation.

with separate schooling systems, many Malaysians grow up in ethnic silos, which fundamentally hinders national unity even beyond any legal framework

The most amusing part of Malaysia's discrimination is in the term "bhumiputra," which is Sanskrit for "son of the soil," but today it's used for Malay muslim.

All these lands were Dharmic originally, all the way to Japan, before the various cults arrived.