This ain't pixel art. Your last screenshot is 1280x720 and has a size of almost 1MB. This is madness. Learn how to use lossy webp. With compression 80 that screen is 48kb instead of 983kb. Even with placebo setting of 100, it only is 176kb.
Do a test sample. Create webp of 100 95 ... 50 and mix it in with the original. Cycle through the images in a way that you do not know which image is displayed. Try to tell the difference.