All past agreements are null and void when china "tried" to unilaterally change the status quo in 2020 therefore, this joint statement from 2005 is also null and void. Only agreements that have value are those which were negotiated after the de-escalationI don't think in modern times, there is not "suzerainty"
The Indian side reiterated that it recognized the Tibet Autonomous Region as part of the territory of the People's Republic of China and that it did not allow Tibetans to engage in anti-China political activities in India.
Joint Statement of the Republic of India and the People’s Republic of China