Yes, the Z690-E does this sometimes (I think all Asus Z690's do it, but not sure about that). I usually notice it when I have completely disconnected power (i.e., power supply OFF or unplugged, so no 5v standby to board). On a normal "restart" from windows, it does not happen.
Scared the heck out of me the first time I powered up my build! Double-checked everything, hit the power switch, lights came on, all looked good, then it suddenly powered off. I thought something was shorted or misconnected. But then it powered back on and continued booting just fine. I wish ASUS had included some kind of warning pamphlet with the board advising of that behavior.
I recall some discussion of this on the forum shortly after the board was released. I *think* (my memory isn't perfect) ASUS said it had something to do with overclocking (including "Asus Optimizations" which default to Enabled in bios), where they had to power-reset the processor during boot to enable certain changes they did not want enabled at initial power-on. The search function isn't great here but you may be able to find that old discussion, in which an ASUS rep did respond it was "normal" and a vague reason why they did it.
Same here -- I tried the AI overclock stuff, and decided it was more trouble than it was worth. I concluded my 12900k was fast enough for me at stock.
I don't recall all the details (I built my system Mar-2022), but I *think* the discussion said that if all the "auto" features (memory, "asus multicore enhancements", etc.) are all disabled, that eliminates the initial power-off that happens in a "cold" post. It was something about memory detection or switching some feature of the processor that required a power reset to enable. I just decided to live with it, since I rarely power off the system anyway.
I searched a bit but can't find the old threads. I will look a bit more, and post again if I can find it.