The Bug:

Debug messages aren't prefixed with gray color indicators despite being system messages.

The 1.19.1 Pre-release 4 changelog states that

System message are now displayed with a gray color indicator

This means that any messages that are displayed by the system, for example, command feedback, are prefixed with a gray color indicator. Despite messages displayed through using debug functions being considered system messages, they are not prefixed with gray color indicators.

Steps to Reproduce:

• Display a system message in chat by adding a tag to yourself by executing the following command.

• /tag @s add test

• Take note of how the command feedback message is correctly prefixed with a gray color indicator as it's a system message.
• Use any debug function, for example, F3+B.
• Take note as to whether or not debug messages are prefixed with gray color indicators.

Observed Behavior:

Debug messages aren't prefixed with gray color indicators despite being system messages.

Expected Behavior:

Debug messages would be prefixed with gray color indicators.