On the dangers of online communication

There's a good sci-fi film with Bruce Willis (made before the end of his career ) called Surrogates, about a future where people live partially "online" in a virtual world, while their bodies grow fat and age somewhere in a dusty apartment. The film echoes the ideas of various science fiction writers—Strugatsky, Lem, Lukyanenko. However, even these guys would be surprised to see how we've all been "digitized" during the COVID-19 lockdown. Study, work, communication, dating—all of this has taken on a new, fashionable "online" format.
Some of you might think this is progress, but I agree with the main character, for whom the plot was a dystopia. I'll try to explain from a biological perspective what will happen to us in the "online" world:

The online work/study format leads to a kind of social isolation, which in turn can lead to depression and other mental disorders due to a decrease in BDNF and levels of certain neurotransmitters. To understand this, go to a zoo and compare the appearance of solitary animals with those in pairs/groups.

The online format leads to a decrease in physical activity, which leads to problems with blood vessels and lymphatic drainage, which leads to varicose veins, hemorrhoids, prostatitis, and other nasty ailments that used to be found only in old people.

"Online" leads to persistent vitamin D deficiency.

Due to the above-mentioned reasons, a person's immune system activity decreases ("stay home, stay safe" is a slogan for idiots)

Online eating leads to weight gain due to fat, since energy is not expended and access to food is unlimited.

Men who work online for long periods of time without real-life contact with women experience a drop in testosterone and an increase in prolactin levels (I call this "IT guy syndrome "). This is partly why "Tinder machos" may not understand how to interact with women in real life. Similar processes also occur in women who rely on Instagram.