Problems in bright sunlight. sight does not last. - Vector Optics Frenzy 1x 20x28mm Red Dot Sight

I started target shooting handguns 3 years ago and bought a Vector Frenzy in 2019. It seemed to work well and I ended up buying seven more. I had problems with zeroing with one and a very dim dot on another after about a year. I thought the American address was their main one but I ended up dealing with someone in China. They argued about the warranty and kept asking for pictures and made it sound like I was doing something wrong. Eventually the two sights were replaced. Now I have one sght with no dot on high setting and two more with very dim dots on 8 and barely visible on ten. I shoot at an outdoor range so I often shoot in bright sunlight and these sight don't seem to up to the job after being used for a short time. Save your money and buy a sight that works well in all light conditions and honors their customer warranty.