I replaced the light fixtures with a new ones after painting the laundry room and bathroom. The lights came on normal and about a minute later dimmed. I did not do this at the same time. I did the bathroom about a week ago and the laundry room today.

I am a bit confused, did both fixtures dim or just the first one?

I week ago I replaced the bathroom light. A few days later the light dimmed. A few days after that it went out and I replaced the light. The light was normal. Today I replaced the light in the laundry room and soon after replacing the light The light dimmed. The one in the bathroom dimmed also. In the last few hours the both have dimmed and come back to normal. It seems the change every few minutes. Just a few minutes ago the completely went out.

Most likely a loose wire in the circuit. Check at the breaker, then the switch and finally the fixtures. Fixtures is the least likely place but I think think you have one wire loose and it can be the white neutral