The interview stages went as follows:
1. Recruiter phone screen
2. 60m talk with an engineering manager
3. 90m live pair coding interview, including code review
4. 60m high-level technical discussion with two engineers
5. 60m talk with an engineering manager
The interview process was quite fair and enjoyable, and gave me a great impression of the engineering team. However, the offer stage was regrettably bad.
Following the final stage, I received a voicemail late on a Friday afternoon, which suggested that we talk on Saturday (I view willingness to work over the weekend as a red flag). I finally spoke with that person on Monday, and received a verbal offer that would explode by end-of-day Wednesday. I asked for more time to decide, and they refused, adding that they could reach back out to me in a few weeks. The offer itself included a lowball salary of $135k.
To me, it seems that the exploding offer was merely designed to pressure me into hastily accepting a lowball offer, and that the "reach back out in a few weeks" follow-up was designed to wait out whatever concurrent offers I may have received.