but if vehicles can respawn, that is, vehicle is the subject in your sentence, then the correct reads "The vehicle has not respawned yet". On the other hand, if something or someone can respawn a vehicle, than the correct is "The vehicle is not respawned yet (by someone or something).
I would like to correct a mistake of mine: in both situations "the vehicle" is the subject (no matter whether active or passive voice). What I wanted to mean is: if "the vehicle" can respawn, that is, it can perform the action of "respawn", than you may use the active voice: "the vehicle has not respawned yet". But if "the vehicle" suffers the action, that is, if it can be respawned (by someone or something), then you may use the passive voice version: "the vehicle has not been respawned yet." The point is not whether "the vehicle" is the subject, rather whether it performs or suffers the action.
A screenshot is taken, you will be reported.
A screenshot has taken, you will be reported.
He is fallen (died).
He has fallen (died).
The vehicle is not respawned yet.
The vehicle has not respawned yet.
The sentence "The vehicle is not respawned yet" is wrong because of the verbal tense. The sentence is in the simple present, so the use of "yet" is not appropriate. On the other hand "The vehicle has not respawned yet" is OK.
To summarize, note that there are three distinct cases in your examples:
(1) Present perfect (always formed with the auxiliary "have" plus past participle.
1a) The window has broken. (here "broken" is the past participle "break" which works as an intransitive verb)
1b) The vehicle has spawned.
1c) He has fallen.
1d) He has risen from the dead.
(2) Passive voice
2a) The window was broken. (Here "broken" is the past participle of "break" which works as a transitive verb (someone broke the window.))
2b) The vehicle has been spawned.
2c) He was risen by his Father.
(3) Verb to be + adjective
3a) The window is broken. (here "broken" is an adjective)
3b) Christ is risen!
3c) He is not fallen.
(Regarding your original post I said that "He is fallen" was incorrect - I was wrong as Bhaisahab pointed out, it is correct, but "fallen" works as an adjective - like "He is dead".)
Two final notes:
N1 The situations (1) and (2) above are not mutually exclusive, you can use the passive voice and present perfect at the same time as in "A screenshot has been taken" or "The vehicle has been respawned." Those are the situations you have to use "been".
N2 There are situations in which it is difficult to decide whether the construction follows (2) or (3) above. For instance "It is done." You may interpret it as a passive voice (someone did it) or you may say that "done" works as an adjective - that is the way it is, it is "done".
PS Not a native speaker
