Siri disappeared after iOS update

Settings > Screen Time > Content & Privacy Restrictions, turn it off or at least allow Siri & Dictation under Allowed Apps.

Use parental controls on your child's iPhone, iPad, and iPod touch

https://support.apple.com/en-us/HT201304

You can add a screenshot by tapping the camera icon in the bottom left corner.

What phone are you using? What iOS version is installed? Are restrictions enabled?

Stupid question, but have you restarted your phone?

Glad it worked out for you.