If a boss bar's text has strike though or underline in it then it will override the player's name in the tab list. This does not occur with normal text and the underline/strikethrough text still has the shading applied to it. Clone of MC-193524 (Don't know why it created 2 bugs)

In order to replicate:
1. Go onto server or LAN world with >1 player

2. Create boss bars with strikethrough/underline using these commands:

/bossbar add strikethrough {"text":"ABCDEFGHIJKLMNOPQRSTUVWXYZ","strikethrough":true,"underlined":true}

/bossbar set minecraft:strikethrough players @a

To create more add a number after the strikethrough on both commands strikethrough2, strikethrough3, strikethrough4