In the second Guardians of the Galaxy film, we learn that Ego is a Celestial. This is big deviation from the comics universe, but that is fine, this is a different universe. However, my understanding is that the MCU universe still belongs to the same Marvel multiverse as the all the comic universes.
In the X-Termination crossover, we see that originally there was one universe, containing the Celestials and that they split it apart into the multiverse to imprison the Exterminators between the universes. In fact Celestials seem to be commonly portrayed as being giant robot things and having powers that can reach across different universes within the multiverse, so one would expect them to be similar even in the MCU.
Ego on the other hand appears alone in the MCU, with no way to reach Celestials in other universes, and has come into being entirely within the MCU. He also takes a drastically different form.
Is there any precedent in the comics of other Celestials deviating this much from the common portrayal?
He does appear to 'seed' life on planets around the universe like other celestials, albeit in a slightly more conventional form.