Vbi shrinks (grows) under forward (reverse) bias.

The same laws apply, but Vbias modulates the Fermi level in both p and n type regions, and these new Fermi levels must get matched again in the depletion region, so Vbi changes in order for equilibrium to be established.

There's some good info on this at the net. Try Google searching images for this. Hyperphysics talks about it too.

$V_\mathrm{bi}$ shrinks (grows) under forward (reverse) bias.

The same laws apply, but $V_\mathrm{bias}$ modulates the Fermi level in both $p$ and $n$ type regions, and these new Fermi levels must get matched again in the depletion region, so $V_\mathrm{bi}$ changes in order for equilibrium to be established.

There's some good info on this at the net. Try Google searching images for this. Hyperphysics talks about it too.