When I try to watch a new movie on Netflix, I get red and blue blurs on my TV.
I have never seen a video image look like that. We do however need some more information. I can see from the image that it's an Onn TV, but is it a Roku TV, or do you have a Roku player connected to it? If it's a player, what model number?
That image doesn't appear to be related to WiFi signal strength, but we still need to know how your Roku is connected. Is it WiFi or are you using an Ethernet cable connected to a network switch? What is your Internet speed?
Does it happen with other services? As noted, is this a Roku TV, or do you have a Roku device connected to it? If it uses an HDMI cable, make sure it's properly seated at both ends. If it's a Roku stick, make sure it's properly plugged into the TV.