It struck me as a countdown timer telling the guys that they're out of time (death date?) and sorely need to hurry, in a visual form suggestive of football scoreboard's time-left-in-quarter countdown (to those familiar with such a thing, as these guys would be) to hint at where they should look.
Shout by TheNightWolfBlockedParentSpoilers2021-04-24T05:48:02Z
I don't think that "clock" was a scoreboard, to me the first thing I thought is more likely right, a timer. A timer that is counting down, as in a bomb, and the Brothers are running for their lives because it's about to blow.