I need to play a Video with transparent background on our website. It works perfectly on Windows, Mac & Android (in all browsers). On iPhone however, no matter what Browser, The transparent parts of the video act almost like an "overlay", making everything behind it a lot brighter. This effect gets worse, the higher I set the iPhone screen brightness. This is of course not the behavior I'm looking for. The Video Element has two listed sources. One .WEBM (VP8 with alpha channel) and one .MP4 (HEVC with alpha channel). I am sure, that something is wrong with the MP4 file, but I don't understand why it works in Safari on Mac, but doesn't on iPhone. Shouldn't they both play the same File? Here is my workflow: masking the subject in DaVinci Resolve exporting as QuickTime - Apple ProRes 444 - "Export Alpha" using Shutter Encoder (v15.7) to convert the file to H.265 (.mp4) under "Advanced Features": Hardware acceleration to "OSX VideoToolbox" & check "Enable alpha channel" also converting the first file to VP8 (.webm) with "Enable alpha channel" then adding the Videos to the website like this: <video height="450px" autoplay loop muted playsinline disablepictureinpicture> <source src="(url of the mp4)" type='video/mp4; codecs="hvc1"'> <source src="(url of the webm)" type="video/webm"> </video> Here is how it looks on Safari (Mac) This is what it looks like in any browser on iPhone I have re-exported, re-converted and re-implemented it multiple times and I just can't get it to work on iPhone. Does anyone have an idea, what the cause could be, or what I can do differently?