Hello,
From time to time, TSP.gov has regular site maintenance and downtimes depending on the calendar. Generally, they schedule these maintenance events. For reference, please take a look at their site downtime and maintenance calendar:
https://www.tsp.gov/holiday-and-scheduled-improvements-calendar/
You can also take a look at their news bulletins which sometimes post planned site outages as well:
https://www.tsp.gov/news-and-resources/plan-news/
Best regards!
