Oh, nicotine is way worse. It may not harm your health directly, but addictiveness is exponentially worse.
Wikipedia: Caffeine - Dependence and Withdrawal: Moderately physical dependence and withdrawal symptoms may occur upon abstinence, with greater than 100 mg caffeine per day, although these symptoms last no longer than a day
Wikipedia: Nicotine withdrawal: Symptoms are usually strongest for the first few days and then dissipate over 2–4 weeks (…) In a minority of smokers, cravings may persist for years.
Edit: Left out the “Caffeine” in “Caffeine - Dependance and Withdrawal”
Edit to add: Caffeine withdrawal causes you to be annoyed for a day. Nicotine causes real, actual cravings (you know you need nicotine, whereas for caffeine you’re just generally “moody” - most people don’t feel “i need caffeine, now”, and even if you do, chances are, if you run out of coffee and can’t get it within less than a day, the “craving” just stops).
For some, many of whom I know, quitting nicotine is downright impossible due to the cravings. For quitting, toning down is key. Those that quit either relapse momentarily in times of stress (usually for about a week or so), or complain of very strong cravings every few weeks/months.
Additionally, nicotine isn’t the only addictive compound in cigarettes, and from what I’ve heard, vaping, gum, etc. just isn’t it for some - people also get addicted to cigatettes themselves.
Not to mention, vaping causes pneumothorax and all the other alternatives cause some harm as well, although much less than cigarettes proper.
Dark mode can be recreated using extensions, although the colors most likely won’t be as legible as “native support”.
I don’t see why a similar extrnsion couldn’t change the timezones of clocks.
Additionally, I don’t see why the server should bother with either (pragmatically) - Dark mode is just a CSS switch and timezones could be flagged to be “localized” by the browser. No need for extra bandwidth or computing power on the server end, and the overhead would be very low (a few more lines of CSS sent).
Of course, I know why they bother - Ad networks do a lot more than “just” show ads, and most websites also like to gobble any data they can.