Does terrastalization convey Ice/Snow or Ground/Sand benefits?

Question

Basically the title, but in every direction and flavor:

An Ice type terastalizes to Steel: does it lose its defense buff from snow?

A water type terastalizes to Ice: does it now get a defense buff from snow?

A Rock type terrastalizes to Grass: does it lose its special defense buff from sand?

A Fairy type terastalizes to rock: does it gain a special defense buff from sand?

Comments

I don't know for sure, but I think Terastal Pokemon always act like they have only one type, except when they get STAB for the types they had before.

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I've got you

Answer 1

Summary:
Gargancl -> Ground loses Special Defense buff in Sandstorm.
Source: https://replay.pokemonshowdown.com/gen9nationaldex-1739513683
I lost the other footages, but
Regieleki -> Rock gave it the Special Defense buff in sandstorm.
Corviknight -> Ice gave it the Defense buff in snow.
Regice -> Steel lost the Defense buff in snow.

Hope I helped!