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Safari Flashing

I'm running macOS 11.4 and I've started to notice that when I use YouTube in Safari, the content flashes. When I leave my cursor alone and the controls for the videos disappear, my screen starts to flash like it's glitching. I've watched the same video side-by-side on Edge, Chrome and Opera and the issue is only on Safari, so it's definitely not a hardware issue. Obviously I don't want to change browsers because Safari is the fastest for my Mac. Has anyone else had this issue?

Posted on Jun 4, 2021 11:08 AM

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Question marked as Top-ranking reply

Posted on Jun 5, 2021 3:24 AM

Go step by step and test.


1. Update Safari, if an update is available. Update may come with bug fixes.

    https://support.apple.com/en-us/HT204416

    https://support.apple.com/en-us/HT201541


2. Quit Safari, launch Safari holding the Shift key down.

    https://support.apple.com/en-us/HT203987


3. Startup in Safe Mode. https://support.apple.com/guide/mac-help/start-up-your-mac-in-safe-mode-mh21245/mac.  

    Quote:

    It also does a basic check of your startup disk, similar to using First Aid in Disk Utility

    And it deletes some system caches, including font caches and 

    the kernel cache, which are automatically created again as needed.


4. Clear History

    https://support.apple.com/guide/safari/clear-your-browsing-history-sfri47acf5d6/mac

    Please read the article before clearing history, 

    this is like a low level resetting of Safari without affecting passwords and bookmarks.


5. If Safari doesn't open a webpage or isn’t working as expected

    https://support.apple.com/en-us/HT204098

1 reply
Question marked as Top-ranking reply

Jun 5, 2021 3:24 AM in response to Rbache3012

Go step by step and test.


1. Update Safari, if an update is available. Update may come with bug fixes.

    https://support.apple.com/en-us/HT204416

    https://support.apple.com/en-us/HT201541


2. Quit Safari, launch Safari holding the Shift key down.

    https://support.apple.com/en-us/HT203987


3. Startup in Safe Mode. https://support.apple.com/guide/mac-help/start-up-your-mac-in-safe-mode-mh21245/mac.  

    Quote:

    It also does a basic check of your startup disk, similar to using First Aid in Disk Utility

    And it deletes some system caches, including font caches and 

    the kernel cache, which are automatically created again as needed.


4. Clear History

    https://support.apple.com/guide/safari/clear-your-browsing-history-sfri47acf5d6/mac

    Please read the article before clearing history, 

    this is like a low level resetting of Safari without affecting passwords and bookmarks.


5. If Safari doesn't open a webpage or isn’t working as expected

    https://support.apple.com/en-us/HT204098

Safari Flashing

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