Indent is a YC startup, and one of its founders, Dan Gillespie, previously co-founded a startup that was acquired by CoreOS, which was later acquired by RedHat and subsequently IBM.
Yc startups founded by a founder who sold the previous startup
Insquad is a YC startup founded by Alex Svinov, who has co-founded and exited four successful startups.
Rippling is a YC startup that participated in Y Combinator's W17 batch. It was founded by Parker Conrad, who previously founded Zenefits, a startup he sold before founding Rippling.
Gym Class - by IRL Studios is a YC startup (W22 batch) and one of its co-founders, Paul Katsen, previously founded a startup which he exited to Coinbase.
Marr Labs participated in Y Combinator (YC batch W24) and was co-founded by Han Shu, who previously co-founded Wyth, which was acquired by Airbnb, indicating that he sold his previous startup.
Bimaplan is a startup that participated in Y Combinator (W21 batch) and was founded by Vikul Goyal, who previously founded Carcrew, which was acquired by TVS Group.
Mino Games participated in Y Combinator (YC Summer 2011), and one of its co-founders, Josh Buckley, built and sold gaming companies as a teenager. Additionally, the CEO, Sash MacKinnon, also built and sold gaming companies as a teenager. This satisfies the criteria of being a YC startup founded by a founder who sold their previous startup.
Kopia is a YC startup (W23 batch) founded by Calvin, who previously founded an ecommerce startup that was acquired for close to 8-figures.