where is the "3D" tab

Adobe began warning about the discontinuation of the old, outdated 3D features a few years ago, so they are no longer part of Photoshop. You can read an explanation in the article below, which was posted over a year ago:

Photoshop 3D | Common questions on discontinued 3D features

At about the same time as the outdated 3D features were being removed from Photoshop, Adobe acquired the powerful Substance 3D applications which are much more current.