I think what's happening is that. Bhutan has always been a symbol of loyalty in the subcontinent. No matter what problems happened, there has been no problem with Bhutan. All these encroachment on Bhutan, these land territory, lobbying in Bhutan etc etc is to make Bhutan distant from India.
Foreign people like to say that Chinas foreign policy is like Go. You need to isolate your opponents, and surround them with your own cards. Make them feel like boiling, anxiety, hopeless - these psychological stuff are what the Chinese focus on. It doesn't work on US because they are stronger. But in Indias case, it's slightly different - due to 1962, we won't be reckless. We will calculate their moves again and again. Taking time, while they have first mover advantage.
Either way, Bhutan is a small pawn for China in the grand scheme of things. It might have utility but making india look weak is the main deal. China doesn't want India to be arrogant - which really means that China doesn't wants India to think itself as powerful. It's still the same India that was after 1962 and China is superior - that's their goal. A broken country with broken future.
They might have given Bhutan a package deal that Bhutan will find hard to resist. But here is the thing. China most of the time in foreign policy at least starts out hard but tumbles later on. In BRI, on Pakistan, Sri Lanka, Nepal. If we map the trend of the past, it will mean that we might lose Bhutan. But then their arrogance will kicked, and like always they will bully more then they will gift. Eventually, Bhutan will be back in the fold. But it will be too late by then
China will have encroached, India's relation with Bhutan will not be the same, there will be suspicions like now with Nepal, Sri Lanka.