The 'line-break: anywhere' declaration allows soft wrapping around every typographic character unit, including around any punctuation character or preserved spaces, or in the middles of words. It disregards any prohibition against line breaks, even those introduced by characters with the GL, WJ, or ZWJ character class (see UAX 14) or mandated by the word-break property.
Chrome's implementation of the 'word-break: break-all' feature tries to match Edge, and the current spec draft, so that it ignores code points like "." (FULL STOP), which is categorized as IS. in UAX 14. However, end users seem to prefer Firefox's and Safari's behavior, although it is not completely spec complaint. So, the CSS working group resolved to introduce a new value for the line-break property to complement what 'word-break: break-all' provides (matching Firefox and Safari but also users expectations).
Docs: Not available yet.
Explainers: https://github.com/w3c/csswg-drafts/issues/1171