Recent Samsung Galaxy S8 update breaks fast charging for some owners

Unsurprisingly, affected users have voiced their concerns over the internet. There are multiple appeals for help on Twitter as well as a number of threads on the Samsung community forums:
@SamsungSupport my s8 stopped fast charging after the latest update. It takes almost 6 hours to charge. HELP!
— Marielena Hernandez (@9a51831a9c4f445) November 26, 2017
@SamsungSupport GM, My fast charger for my galaxy S8 just stopped working. I now say 5 hours to charge. I went into settings to see it fast charger was still on & it is. Can you help please? Thank you!
— Etica (@justeeks) November 13, 2017
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