These are characters which can be built from multiple glyphs, but they also have a pre-built Unicode point. There are also ligatures that combine multiple characters into a single code point.

The extension can be tricked by invisible Unicode Tag Characters-special symbols unseen by humans but obeyed by AI.

A new JavaScript obfuscation method utilizing invisible Unicode characters to represent binary values is being actively abused in phishing attacks targeting affiliates of an American political ...