Apple Pencil 2nd generation - this piece appeared i dont know where from and now my pencil isn’t working properly

Looks like your Pencil is damaged and something broke off the transducer/sensor rod of the Pencil.

Time for you to search online for your nearest, “local” Apple store location and call contact phone numbers and call to make an appointment to have your Pencil looked at and options presented you.

Failing that,

You need to contact Apple support via the contact support link located at the upper right hand corner of every Webpage of these Apple support communities.

Use the Hardware Repair and Device Performance support categories.

OR

by installing and using the Apple Support app found in the iOS App Store.

Tap the iOS App Store link below.

https://apps.apple.com/us/app/apple-support/id1130498044

OR

Call contact Apple via the support numbers found in the link bekow.

Contact - How to Contact Us - Apple

Tap the link below.

Contact - How to Contact Us - Apple

Best of Luck to You!