Macbook pro with (probably) an hardware problem - video

I recently bought an Apple MacBook Pro 2018 15 '. The computer is less than a month old so I can not compare before and after the Mojave update. On Safari (on Chrome it seems not) I have a problem with full screen videos. Not always, but once in a while, some pixels (not all) become green for a few milliseconds. Sometimes the problem reoccurs reproducing the same video. It does not happen in applications, only on browsers. Once, I had a similar problem with the browser scrool, navigating within a web page.

Contacting Apple support I was told to reset the SMC chip, which I did and the green pixels seem to have disappeared for now.

The problem is that now, perhaps in place of the green pixels, appears as a disturbance (a micro interference if you can call it that) but always on Safari.

In fact, trying to put a video on Chrome in Youtube the sembran problem does not appear, no resolution and no downsizing (neither in player nor full screen). I add that on Netflix in 20 minutes of video playback the problem did not occur neither before nor after resetting the smc.

What do you think it could be? Safari not 100% optimized for Mojave? A PC software problem? A hardware problem?

Thank you so much for the help I hope you will give me. I apologize for English, unfortunately it is not my mother tongue.

Kind regards,

Massimiliano (cesare190)