My Siri isn’t listening whether Siri is on.

Perhaps double check all settings, and then re-set them again.

Something is amiss in that device; it also hands-off to others.

What else does this iPad see when in use? An iPhone, a Mac?

Various links follow, that may (or not) correct its issues:

Update iPadOS - Apple Support

Use Siri on iPad - Apple Support

How to Set Up and Use "Hey Siri" on iPhone and iPad - How-To Geek

Use Siri on all your Apple devices - Apple Support

Use Siri on iPhone - Apple Support

Devices that support 'Hey Siri' - Apple Support

iPadOS 16 - New Features - Apple

Find out what Siri can do on iPad - Apple Support

Change Siri settings on iPad - Apple Support

About iPadOS 16 Updates - Apple Support

Settings in iCloud may also affect how all things shared

there will work. Sometimes you may login to icloud in a

browser, to change or view settings. With most devices.

If your iPad is not up to date with latest version its

hardware supports, it may be missing important

parts that otherwise may cause it to fail to function.

The troubleshooting of these issues may take quite awhile.

And sometimes if you've a backup saved, to another device

then you might be able to wipe or reset/reinstall the iPadOS.

Good luck with iPadOS!🌞

Siri will only be listening if you have enabled two specific settings:

Settings > Siri & Search > 

• Listen for “Hey Siri” - set to ON
• Allow Siri When Locked - set to ON

If these two settings are set to OFF, Siri will only be active when manually triggered by pressing the Top (Sleep/Wake) button - this being (a) significantly more secure in not having an active “hot microphone” - and (b) is more power efficient.

More information can be found within the iPad User Guide:

Use Siri on iPad - Apple Support

Be aware that many older models of iPad only support the “Hey Siri” wake-up command only while the iPad is connected to its Power Adapter. Later models of iPad can use this feature while operating on battery power alone.

See >>> Devices that support 'Hey Siri' - Apple Support