What causes weird spots on my iPad screen?

Hello, I spotted weird particles spots on my actual screen! I tested with full white wallpaper but I didn’t found any black or bright spots, means dead pixels. I Thought that maybe its condensate and I added some rice on a paper on my screen. I have this ipad 10 for 6 months, using it only with screen glass protection, didn’t drop it once. The ipad works normal but I want to know what are those. Can you give some advice? Thank you

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