I think China sees the opportunity to create more economic ties with India and use that as soft power to shift the political stance there to be more favorable to BRICS. The US is providing a unique opportunity to do that right now by being incredibly belligerent towards India. The same opportunism that drove India to the west can also keep it in BRICS orbit once the economic gravity shifts towards trade with the global south. The companies and oligarchs in India will want to continue maximizing their profits, and with the west going into economic decline, their only option will lie with BRICS.