Spotted on Mozilla's bug tracker:

[meta] Homepage Sports Widget

Where it turns out the countdown widget was part of a broader plan to add a different permanent widget:

• "Phase 1: Countdown"
• "Phase 2: Follow a team and View Schedule"

Web calls will apparently be providing

• SportsMatch
• SportsTeam
• MatchStatus
• TournamentPhase

You can also expect a popup on the Desktop that advertises World Cup wallpapers.

The Phase 1 wallpapers and widget remind me of 2017 when they rolled out the creepiest experiment possible and then apologized with language that would be at home today:

"Although we always have the best intentions, not everything that we try works as we want," said Jascha Kaykas-Wolff, Mozilla's chief marketing officer... "This was not a paid promotion but rather a collaboration that was intended to be fun."