They replaced Google Assistant with Gemini; it was opt-in for a minute but I guess they decided to turn it on for everyone. I think at some point the default action for long pressing the power button turned into summoning it.

I personally opted in, so I didn't notice when they completely axed assistant, but it was stupid that I had to turn my power button back into a... Yknow, power button. I don't need an AI button on my phone, and I can't imagine most people do.