How to Transfer a Youtube Channel to Another Account - Mira Violet
Google's docs will tell you it's not possible but I found a workaround for how to transfer a youtube channel from one personal account to another.
miraviolet.com
support.google.com/youtube/thread/1585512?hl=en
How to move history and liked videos from one account to another? - YouTube Community
support.google.com
This is done by transferring ownership of the channel to another Google account.
Therefore the channel needs to be linked to a Brand Account .
See reference : https://support.google.com/youtube/answer/4628007?hl=en
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I've solved most of it by using Youtube Copier (https://ctrlq.org/youtube/playlists), although I realized that "Liked" playlist isn't mergeable at all!
Unless you have sort of 2000 liked videos on the old profile like me, just try to re-like them all!