The three million toothbrush botnet story isn’t true.
Here’s the original source of the story: https://archive.is/2024.01.30-203406/https://www.luzernerzeitung.ch/wirtschaft/kriminalitaet-die-zahnbuersten-greifen-an-das-sind-die-aktuellen-cybergefahren-und-so-koennen-sie-sich-schuetzen-ld.2569480
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That page is old enough that it doesn't seem to support HTTPS. If your browser automatically converts HTTP to HTTPS, you're going to get a warning about an insecure connection. Here's a wayback machine link that supports a secure connection: