The player-tracking markers store their player's username in their data.username NBT field.
With that, they also store the format of the text provided.
This is used to upgrade the text when necessary

These text format numbers correspond to the minimum compatible pack format:
8: 1.18-1.21.4 (21w37a-1.21.4)
62: 25w02a
63: 1.21.5 (25w03a-1.21.5)