4 points
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You are confused. What you are describing applies to transferring copyright, not for granting a license while retaining the copyright.
If things worked the way you described, free software, for example licensed through the GPL, couldn’t exist because then the authors could always take away the users’ rights by retroactively revoking their license. Fortunately, it doesn’t work that way.
2 points
There are cases where artists withdrew consent and their work had to be taken down, and to my knowledge all contracts can be amended or cancelled, especially if they’re exploitative like reddits. You have a right to compensation if they profit off of your creative work, be it artwork, music, or writing.