It would likely depend on how Sony sought protection in India.
I would imagine Sony files an international TM application at the World Intellectual Property Office. This means they applied through one application at WIPO and designate every country they intend to trade in, they then have to wait for each individual domestic registry to examine the trade marks. Some TM registries are quicker than others, it may be that Sony filed their international application at WIPO years ago and have only recently received the examination report back from the Indian registry.
It doesn’t matter in my opinion, Sony will easily be able to have the existing PS5 registration invalidated on the grounds that the application was made in bad faith, it was applied for to confuse consumers and sell counterfeit goods.
Failing that, they could potentially seek invalidation on the grounds that the PS5 registration is confusingly similar to previously registered PS4 marks owned by Sony