I expect the pnpm maintainers to be familiar with it because bun is one of the other three or four major JavaScript package managers. To put it another way, if you gathered up the 100 people in the world working on the most similar problems to pnpm’s own work, like 15 or 20 of them would be working on bun.

I believe the objective verdict on the rewrite is “actually, everything went better than expected”, but it was and seemingly still is quite controversial and engendered a fair bit of bad blood, which I would have thought would be undesirable or demotivating to maintainers.