It's SWEs as well. Leetcode grinding isn't hard if you have an Applied Math background, like a large portion of IBankers. Ironically, I don't meet many ex-IBs as a PM.

Edit with additional anecdote:

A friend of mine who works IB told me how most of SF's Goldman Sachs Analysts (new grad IBs) class in 2020 and 2021 left for tech (either PM or SWE) because you earn more as a new grad FAANG dev than as an IB Analyst ($90k base and variable bonus that ended up pushing TC to around $150-160k with 60-70 hours of work).