ESP32-C6 IO21 Glitch on Boot

[chrismerck]

We've got a blank (fresh from Espressif) ESP32-C6-MINI-1. We notice that there is a very brief positive pulse outputted on IO21 when the IC boots up. Less than 10 uS. Still, this is long enough to turn on a MOSFET we have connected which resets another microcontroller, causing a bootloop. We found that IO15 does not have this glitch on boot.

Any idea what may cause this pulse? Are there certain pins expected to have a glitch on reboot of the C6?

[boarchuz]

Check Appendix A of the datasheet, where GPIO21 is one of the pins that has pullup enabled at (but not after) reset.