Transparency problem

Hello, i need smooth animation of emission objects appearing in my project, yet during those animation it looks bad since faces inside can be seen that you would not see on object with emission
I looked online, but only solution i can found is using light path, but it made another problem that light from emission is now blocked by other objects that are not visible yet in animation (this grey block is 100% transparent, yet you can see it) .
I use cycles and can’t change to eevee

Welcome!

This kind of flat, 2D transparency might require compositing or video editing to achieve properly.

The easiest way to do it, if you don’t have that many cubes, would be to first render the animation without the cube, then a second time with the cube and do a cross-fade between the 2 videos in editing.

Then, you keep the second render going until you reach the point where the second cube would have finished appearing, then you render that part again, doing a third render with the second cube fully present and you cross-fade that on top.

You do that for every cube, rendering each section where a cube is appearing twice, with and without the cube present, then cross-fade in video editing.