It could be your paint wasn't mixed well. Just a thought

Ceilings are hard. The fundamentals of painting must be stuck to absolutely. I don’t want to patronize you, but every time I’ve painted a ceiling and had it come out poorly it was because of these two things: don’t stretch the paint (One pass to apply and one to smooth and then re-load the roller. It takes a little longer but comes out better) and keep a wet edge (start at one edge of the ceiling, cover the whole width, and carry that edge all the way across). Also — I started with this but I’ll say it again—ceilings are hard. There’s a reason popcorn ceilings are a thing, they make it easier. Be prepared to accept a finish that’s only, say, 90% perfect. If you’re insecure about it, try looking up at the ceiling when you’re at someone else’s house. They’re seldom perfect, and people hardly ever notice.

Have you been crosshatching consecutive coats? If it’s flat paint it should eliminate the roller marks. Or you could just spray them.

Ceiling painting is harddd. Hard to keep wet edge, hard to keep the consistency of paint thickness. But mainly hard to “remember “ where you stopped and start where you left off. Especially if it’s white on white or same color repainted over.

Must to mix the paint thoroughly for a minute or so if you didn’t buy the paint same day of the paint job. I usually have the paint desk shake up the can.

If the ceiling is patched or mix of old and new (ceiling) materials the paint dries differently but they all catch up in a day. If the ceiling had a leak or touched up by a primer or closer to hotter appliance (read cooktop) fumes it will paint and dry different color,tinge,hue. Best of luck.

as paint dries, it tends to get darker, not lighter