Invisible Unicode text, once an AI attack tool, now used by spammers

A block of Unicode characters that renders invisibly to humans but is machine-readable, previously used mainly to hide prompt injections targeting AI systems, is now being adopted by spammers for other purposes.

Why it matters: It shows a security technique migrating from a niche AI-safety concern into mainstream abuse, which usually means defenses like spam filters and moderation tools need to catch up faster than when it was just an AI red-team curiosity.