Using the reset formatting code §r in an advancement description that spans multiple lines resets the text colour to a default value (grey in the advancement screen; white in chat) after the next line break following the formatting code.

Steps to reproduce:

1. Download the attached data pack “reset_format_test.zip” and add it to a new or existing world. This data pack adds a single advancement that is granted immediately and has the following string as its description text: "Lorem ipsum dolor sit amet, consectetur adipiscing §oelit§r, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua."
2. Hover over the advancement in the advancement screen and in the chat announcement. Note the formatting.

Expected results:

The word “elit” is italicised and the entire advancement description is formatted like normal with a green text colour.

Observed results:

The word “elit” is italicised, but the advancement description loses its green text colour starting at the next line break, turning grey in the advancement screen and white in chat.

May relate to MC-228516, MC-248972, and MC-250160.