If you turn Screen Time OFF and later turn it back ON, the previously recorded Screen Time usage data is reset. The usage statistics will start again from zero, rather than continuing from the data recorded before Screen Time was disabled.
In other words, switching Screen Time off effectively breaks the continuity of your usage history. Once you re-enable it, Screen Time begins tracking your device usage as a new measurement period, so the previous daily and app-usage figures are no longer carried forward.
Therefore, if you want to maintain an uninterrupted record of your Screen Time usage, do not turn Screen Time off, even temporarily.