Where is the undo option in Notes on iPadOS 26?

To undo text edits, swipe left with three fingers.

Or try Shake to Undo.

In addition to the three-finger swipe gesture, or a shake of the iPad (both being configured through settings), you should see the "undo" button at the top of the note:

It should be up

After three-finger swipe

You are very welcome.