That's not why this is weird, the fact that India is shifting deeper into the bRICs is.

China has been a strategic threat to India, between their close alliance and support of Pakistan and the whole kashmir thing, plus the past skirmishes in aksai chin (even in 2020/2021).

Modi doesn't really care about geopolitical history, he lives in the moment, whether that makes sense or not, hence surprise invalidating the currency over a weekend.

But I don't see how a menage a trois works here, especially given India's ties to the US.

This sounds like a Russian demand because they were tired of being paid in weak rupees. Knowing Modi, he'd gladly go along as long as he got a cut, and it hurt Pakistan enough.