Does official OTA ROM update overwrite custom recovery as well?

[Android Central Question]

I used TWRP Recovery before last ROM update (mostly because of its root feature). Currently, I am not able to boot into TWRP recovery.
I tried to boot with ADB: adb boot recovery. And it brought me into stock recovery.
Does it mean my phone has not custom recovery anymore?
(POWER button of my phone does not work)
How can I check it without POWER button?