128 samples with node denoiser animation still flickering I'm trying to do an animation but even if  I doubled the samples my video is flickering, in another topic they suggest me to increase the samples, so I moved from 64 to 128 samples but the result is almost the same.
I'm using a denoiser node, someone told me to try to render without it and then use a video denoiser, but I found a lot of videos tutorial where they use it even with less samples and they don't have this flickering problem so I think there's something not setted correctly in my file, can someone check it or give some advices?
Here you can find the file wth the folder texture and the animation video folder:
https://www.dropbox.com/sh/ubn2ejn51cre75v/AACMnkRHLIz4jDkintteO-eYa?dl=0
I played with light bounces, clamping, filter glossy and caustics settings and I tried to set it to the min possible value without loosing too many details; this have reduced a little bit the noise but still looked so bad.

Then I found a tutorial on youtube, so I removed the neons objects with emission shader and replace it with area lights, with this I've almost removed all the noise

Then I tried to switch from Path Tracing integrator sampling to the Branched Path Tracing and this completly removed almost all noise but increase a lot time render (from 3.00min to 15.00min)

So I tried to decrease the samples number (from 128 to 32) to decrease the time rendering, this added more noise but still look good

Now I will play with settings to adjust it more and increase details and then try to add a denoise node.