Lights flickering, different breakers

Hello!

Currently really stumped. I have lights flickering on at least two individual breakers on my first floor. Second floor is unaffected. All of the lights are LED’s, some of the fixtures include chandeliers and normal overhead lighting. I know two of the circuits do share neutrals in one of the boxes. There are dimmers involved in both circuits but there is also 3 way switches and single pole on some other lights.

Is this a loose neutral in one of the receptacles? A loose neutral in the panel itself? Or is it maybe an issue with the dimmers somehow? Any advice would be appreciated. May call an electrician within the next couple days if I can’t figure it out. TIA!