SDT Duration calculation off

It’s hard to know if this is an issue with v4 or if it was happening the whole time. However, it’s easy to see that it’s wrong now. When we set permanent SDT on something, we typically just change the first digit of the year from a 2 to a 3. Meaning, we change the SDT so it ends 1000 years in the future. In the old UI, it would calculate the duration of the SDT and show it in minutes and seconds. The new UI adds years, months, days, and minutes (at least). For one SDT i just set from 2023-03-23 02:11 PM EDT to 3023-03-23 02:11 PM, the new UI shows 1000 years, 8 months, 2 days, and 59 minutes. Unless there’s going to be a new ceasar and a new calendar (possible), I don’t know why it has anything other than 1000 years exactly. Where did the 8 months, 2 days, and 59 minutes come from?

For reference the old UI shows 365242 days 59 minutes. I get the 365000 days, +/- a few for leap day anomalies. But even in the old UI, where did the 59 minutes come from?