the outdated information could also be removed from / updated on the event series page

https://forum.effectivealtruism.org/posts/YnsRasSzXzRcFCLdr/food-for-thought-event-series

Your assessment of challenges tied to seasonal holidays seems accurate and the subsequent suggestions for mitigating unhappiness are plausibly helpful. Thank you for writing up and publishing this!

Something odd may be happening with the use of the word "OK" though. "OK" conveys adequacy or acceptability. Overall what you've written seems closer to claiming, "it can be difficult to avoid unhappiness during holidays", or, "it's common to be unhappy during holidays".