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OLED doesn't need to achieve the high brightness of an lcd panel as per pixel dimming is far superior to dimming zones.This is apart from the better color volume and viewing angles of an OLED panel.

I have the tab S8 ultra and the MiniLED ipad and while the iPad is significantly brighter, the OLED display looks richer in HDR. I would classify it as a contrast first HDR experience and the iPad being a brightness first.
Absolute brightness is not same thing as contrast level.

Here is a extreme HDR image of light bulb taken with iPhone 13 Pro by a professional guy in this field.
Download it to your S8 ultra and iPad Pro, compare them side by side and you'll be amazed by the difference of brightness of bulb.

For anybody else, don't waste time judging it with any other phone or desktop monitor (except maybe Apple's latest Pro XDR display)
tempImageHHf2IR.jpg
 
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