M31 - the Andromeda Galaxy

I even shoot without a T-ring, and this shaking is probably due to a very good mount—I walk, breathe, fart, and the mount reacts to it. I don’t touch the camera; it’s interval shooting with a timer. Anyway, I’ve been doing astrophotography for maybe a month or two, I don’t understand a thing, I just shoot however it turns out—I couldn’t even get focus back then.

Everything will work out. 150/1000 is an excellent telescope, though it's more for planets, of course. You could try a shorter exposure and take more photos. Focusing is better with a Bahtinov mask. And yes, collimation and balance. Focusing with the mask will take more time, but the result will be higher quality. One night, one imaging target.