Which ethical themes about technology and social media does the Black Mirror episode Hated in the Nation raise?

Technology as a double-edged sword, the amplification of outrage, viral public shaming, groupthink and herd mentality, and collective responsibility for what a crowd does online.

In the episode, a hacker turns government-funded robotic bees into weapons. Whoever is tagged most often with the hashtag #DeathTo on a given day gets killed. At the end, all 387,000 people who ever used the hashtag are killed instead. The themes:

• Double-edged technology: the drones were built to replace extinct bees and then served other purposes (state surveillance through a backdoor, and finally murder).
• Amplified outrage: platforms spread anger and condemnation fast, without context or thought for the consequences.
• Public shaming: individuals are attacked and humiliated without mercy in the digital world.
• Groupthink / herd mentality (Herdenmentalität): people join the dominant opinion without checking the facts or considering the harm.
• Collective responsibility: each participant thinks "it's just a joke, a hashtag game", yet together they cause the harm. That raises the question of what responsibility each person carries.

Go deeper:

• Wikipedia: Hated in the Nation — plot summary and critical reception of the episode.