iPad Air M1 - Most recent iOS 18.2 beta3
i did this two times.
i have multiple photos on my Lock Screen. I can touch to get from one picture to the next.
if I touch enough, it shows me the weather app. From there, I can swipe up for Home and see the springboard. At no point from the start was I logged in (hitting the power button for Touch ID never happened).
This appears to be a security hole.
For help with Lock Screen, please post in the Apple Support Community. The Apple Developer Forums are for questions about APIs and features intended specifically for developers.