where is the party icon?

To my knowledge there are no party icons on the xbox website. For party icons or party chat you will need to get the xbox app for your mobile device to use party chat, or on your computer you can hold windows+g and it will open up an xbox UI where you can
also use party chat.

if this does not help you can you please elaborate on “party icon”?

Yes, they changed some of the iconography with the latest round of Windows and Xbox updates to better display where people are and what they're doing. The headset icon (or Kinect icon) will show if they are in a party using a mic or Kinect for chat.
It'll also show if they're on PC and either using the new Xbox features in Windows with Game Bar, Game Pass, or Discord connections, or an Xbox console. If you're not seeing that represented, please let us know, and we can provide some details on how to report
that bug to the Xbox team.

Best thing to do would be to post and let others support it at the
Xbox Feedback site. Can't guarantee that anything will change, but that's the best place to get it supported and noticed.

Just saw it. Don’t like it and the people i play with are confused about it too. I keep getting invites while I’m in an active party with my friends. They need to return the 3 person icon so it appears next to the name.

That feature actually works