“The difference between 4k streaming and 4k bluray isn't nearly as massive as people pretend... [But] the night battle in the last season looked fantastic on 4k hdr disc.” Reddit · r/4kbluray · 3 years ago
Now for the practical part. Google Images compresses heavily. Here are the for true 4K screencaps: game of thrones 4k screencaps top
Always prioritize PNG files over JPEGs. JPEGs use compression that can ruin the fine detail of a 4K image, whereas PNGs keep the image "pixel perfect." Technical Tips for Using 4K Screencaps To make these images look their best on your devices: “The difference between 4k streaming and 4k bluray
Because "top" can mean "best quality" or "most popular," use these search modifiers to get better results: game of thrones 4k screencaps top