Multi-line string marshal output not using block notation consistently

[CubicrootXYZ]

Describe the bug

Marshaling a multi-line string usually results in block notation, but somehow if adding a colon : to the end of the string or starting with an escaped quote character \" the block notation is no longer used.

hello: |-\n  \n  \"name\"\n

vs

hello: \"\\\"name\\\":\"\n

To Reproduce

https://go.dev/play/p/ehf6lfGE7qW

Marshaling map[string]string{"hello": "\"name\":"} does not use block notation, map[string]string{"hello": "\n\"name\""} uses block notation.

Expected behavior

Block notation being used consistently for all multi-line strings.

Version Variables

• Go version: 1.26.0
• go-yaml's Version: v1.19.2

Additional context

I stumbled across this when trying to add javascript code examples as multi-line strings to an OpenAPI spec file (yaml format).