Not A Bug Bug Report - Mechanics

[Gethsisn]

What type of bug are you reporting? Mechanics

What is the bug?
Illusion showing tera when it shouldnt. In game when zoroark copies a pokemon its unable to copy its tera form. In the current simulator zoroark will sometimes have the tera type on it which would be wrong.

Are you able to replicate it? If so, how?
I start with zoroark to confirm what pokemon it copies. I then switch into said mon and tera it. I then go back into zoroark. In game it appears as un-terastelized, and in the sim it apears as terastelized.

 

[Mathy]

If you look closely, you'll see the disguised Zoroark does not have the Tera icon, but it does show a (fake) type change. This is actually based on the type it shows in the Check Target menu:

So this is all intended.
(If it's appearing differently than I'm explaining, please link a replay next time)