The government of Lithuania actually did an investigation and found that Xiaomi phones spy on their users and contain a (disabled, probably intended for Chinese market) content filter system in their default browser.

Edit: source (in Dutch): https://www.security.nl/posting/721810/Litouwse+overheid%3A+... Source in Lithuanian: https://kam.lt/lt/naujienos_874/aktualijos_875/ka_daro_isman...