Update your browser. If Chrome auto-updated to a version that killed High Sierra support, downgrade to Chrome 116 (available from sites like slimjet.com for legacy OS) or switch to Firefox ESR.
If you are still running on your Mac, you are likely facing a frustrating reality: modern software is leaving you behind. One of the most common pain points is WhatsApp . whatsapp web mac 10.13.6
If none of the above work (e.g., your browsers are too outdated), you can run WhatsApp on a modern computer remotely and access it from your High Sierra Mac. Update your browser