Here is some rare footage, a full colour video of a display of captured vehicles in Moscow.
Aside from being interesting to look at, the video announcer reveals the secret to Soviets seeing Ferdinands everywhere. Showing a Dicker Max, he says "Here, we see a Ferdinand type vehicle..." then, as the camera transfers to an actual Ferdinand "...and here is the Ferdinand itself." This confirms my suspicions that there wasn't any kind of panicked identification of every SPG as a Ferdinand, rather the word "Ferdinand" being used to describe German SPGs in general.
Aside from being interesting to look at, the video announcer reveals the secret to Soviets seeing Ferdinands everywhere. Showing a Dicker Max, he says "Here, we see a Ferdinand type vehicle..." then, as the camera transfers to an actual Ferdinand "...and here is the Ferdinand itself." This confirms my suspicions that there wasn't any kind of panicked identification of every SPG as a Ferdinand, rather the word "Ferdinand" being used to describe German SPGs in general.