On the standards track: Yes
Is Experimental: No
Is Deprecated: No
In Chrome version 4 on 2010-01-25 Note: If both ICO and PNG are available, will use ICO over PNG if ICO has better matching sizes set. (Per caniuse.com.).
In Chrome Android version 18 on 2012-06-27
In Edge version 12 on 2015-07-29 Note: In version 79 and later (Blink-based Edge), if both ICO and PNG are available, will use ICO over PNG if ICO has better matching sizes set. (Per caniuse.com.)
In Firefox version 2 on 2006-10-24 Note: Before Firefox 83, the crossorigin attribute is not supported for rel="icon". The media attribute is not supported for rel="icon", see bug 1603885.
In Firefox for Android version 4 on 2011-03-29
In Internet Explorer version 11 on 2013-10-17
In Quest Browser version 5.0 on undefined
In Opera version 9 on 2006-06-20 Note: In version 15 and later (Blink-based Opera), if both ICO and PNG are available, will use ICO over PNG if ICO has better matching sizes set. (Per caniuse.com.)
Not in Opera Android
In Safari version 3.1 on 2008-03-18 Note: If both ICO and PNG are available, will ALWAYS use ICO file, regardless of sizes set. (Per caniuse.com.)
Not in Safari on iOS Note: Does not use favicons at all (but may have alternative for bookmarks, etc.). (Per caniuse.com.)
In Samsung Internet version 4.0 on 2016-03-11
In WebView Android version 38 on 2014-10-08
Not in WebView on iOS Note: Does not use favicons at all (but may have alternative for bookmarks, etc.). (Per caniuse.com.)