Looks like "Daylight savings time" or "Summer time" has kicked in, or out. In my part of the world, that happened last weekend.
The management of "time" is complex, because "time" refers to your timezone and if, or not, adjustments are made to that time, depending on the season of the year. Remember that how "time" is represented depends on where in the world you currently are.
Right now, it's 21:38 GMT where I am (in the GMT timezone). But in Australia, it's maybe 09:38 (yesterday / tomorrow?). So what is the "real time"?
linux UTC GMT timezone are a good search terms for you to explore.