why do some cassette decks eat tape out of cassettes over 90 min?

Here ya go!
TAPE THICKNESS

Did you know that the longer the tape length (90 and 120 minutes) the thinner the actual tape? It makes sense if you think about it, after all they had to make it fit within the tape deck, but the thinner the tape, the more susceptible to breaking.

Hungry

@yogiboy thanks! makes sense.

Although it has been a while since I used my cassette deck, I do recall that if the capstan, pinch rollers and heads are not kept clean the tape can sometimes stick and cause mis feed.