Not all apps transferred to new iPad. I backed up and used automatic setup

See Redownload apps, music, movies, TV shows, and books from the App Store, iTunes Store, and Apple Books - Apple Support

Go to the apps store. Tap on your account icon in the upper right. Tap on Purchased. Then tap on Not on this iPad. You can download the rest of your apps in there.

Make sure that you are signed into the Apple ID that you used to make the purchases.

What model have you updated from/to? Some apps won't transfer because they're not available for the latest version of iOS.