I mean it's bad news, but they may probably lose 12% of their business vs a 30% stock price drop while still hitting estimates (admittedly at the low end) for revenue this quarter. The price should definitely drop, but why is this not an overreaction?
TWLO guided lower for Q2, coming in below expectations on both profit and sales. Furthermore, Uber may be 12% of their business now, but that company is growing, and this means the market expected TWLO to make even more money with them in the future, which is not happening anymore. This also highlights how concentrated TWLO's business is, and how quickly they can lose a meaningful chunk of their revenue. Lack of diversification means more risk, and maybe the market had not fully priced that in.
For the record, right now Google shows TWLO at $23.65 after hours from an end of day close at $33.94.
That said, it's already at $24.94, up 5% from the after hours price.