Spectator mode bug of F3+F4

First, I became spectator (F3+F4 or /gamemode spectator both ok).

Second, I spectated a creeper, my view changed.

Third, I killed myself to keep the creeper view.

Fourth, I used F3+F4 to switch gamemode, I found my view become normal.

Fifth, I did F3+F4 again, the view became back.

After that, I tired to use /gamemode command, you know what, it doesn't happen! (to change my colored view of mobs)