but they were deprived of prior German citizenship.
Per Tibetan claims, they are citizens of a so called 'independent Tibet'. they were never offered nor received PRC citizenship which was only offered to Tibetans in Tibet after the PRC reestablished control. their descendants are also not PRC citizens, since neither their parents were PRC citizens (but rather Tibetan citizens) nor are they born on PRC territory.
thus they are either stateless, or citizens of a Tibet that nobody recognizes (de facto stateless), unless India offered them citizenship. If it did not, and denied them the citizenship they are entitled to per jus solis, then it is actually India that is persecuting them.
Indeed, the Indian government admits that they are keeping the Tibetans stateless except for a few born in India.