The Bug:

The word "Unrelated" within the "gui.chatSelection.fold" string is incorrectly capitalized.

This string currently reads "%s Unrelated messages hidden" (where "%s" represents a number), so there is no need to capitalize the word "Unrelated" here. In English, when a number is used at the beginning of a sentence, there is no need to capitalize the word that comes after it, and doing this is often seen as grammatically incorrect.

Below, I've constructed a table that states all of the necessary and relevant information regarding this issue.

Affected String:

Before reading the table, please note the following:

• Words colored in GREEN are correct.
• Words colored in RED are incorrect.

Steps to Reproduce:

• Display this string by executing the command provided below.

• /tellraw @s {"translate":"gui.chatSelection.fold"}

• Look closely at the capitalization within this string.
• Take note as to whether or not the word "Unrelated" within the "gui.chatSelection.fold" string is incorrectly capitalized.

Observed Behavior:

The word "Unrelated" is incorrectly capitalized.

Expected Behavior:

The word "Unrelated" would not be capitalized.