The hottest AI startups are raising back-to-back funding rounds. Suddenly, it's feeling very 2021 in Silicon Valley for a chosen few.

Samantha Lee/Insider

In February, Glean announced a $200 million funding round valuing the AI enterprise software startup at $2.2 billion. Normally, a founder would hop off the fundraising treadmill after such a close. But these are not normal times, and Glean has the kind of meteoric revenue growth that lights up the eyes of VCs, more than tripling annual recurring revenue over the past year.