the cat was gone -разве это пассивный залог

gone /gɒn/ /gɑn/ adjective LEFT

1. [ after verb ] If something is gone, there is none of it left
All my money is gone and I have nothing to buy food with.

2. [ after verb ] dead
Fortunately I'll be dead and gone long before the money runs out.
They did everything they could to save him, but he was already too far gone (= too close to death) when the ambulance arrived.
1MDD be gone
a) to be no longer in a particular place:
The door slammed and he was gone.
When someone is gone, they have left the place where you are and are no longer there. When something is gone, it is no longer present or no longer exists.

3 PREP

If you say it is gone a particular time, you mean it is later than that time. (BRIT INFORMAL)
= after, past
gone [gɒn] adj (see also go).
1) (departed, past) уехавший; ушедший.
2) (US, doomed, hopeless) пропащий.
3) (dead) умерший, усопший.
4) (coll, in a stupor, drunk) отъехавший (sl
I turned round for my bag and it was gone.
b) to be dead or to no longer exist:
His wife's been gone for several years.
Many of the old houses are gone now.
➔ dead and gone at dead1 (1)
2 be gone on somebody British English informal to be very attracted to someone of the opposite sex:
Kate's really gone on that boy next door.
3 be five/six/seven etc months gone British English informalMB to have been pregnant for five, six etc months ➔ going, going, gone at go1 (36)

Нет, это по-прежнему НЕ пассивный залог! Подробней см. свой предыдущий вопрос

Это называется Compound Past Form, залог - действительный, а не страдательный.

насчёт правил точно не скажу, но это нормально. в смысле поймут вообще-то)

с точки зрения грамматики - пассивный

Жалко котика )))))