2021 T-Mobile — ~40–54M records; WA court says 2021 SMS notices violated state breach law (2026)

Hacked. 54M records. Update July 2026: King County Superior Court Judge Jason Holloway ruled T-Mobile’s 2021 Washington SMS breach notices to hundreds of thousands of residents (about 361,030 texted consumers cited in coverage) failed the state’s data-breach notification law because texts omitted required content and a webpage hyperlink did not cure the defect as a matter of law; Law360 summarized findings of 722,060 violations. T-Mobile said it intends to challenge the decision; remaining claims including security adequacy set for trial in 2027.