Is it a sentinel value or a sentinel range? There's nothing fundamentally wrong with e.g. having a service begin on May 1st 2028 (2028-05-01) and continue until forever (2025-12-31). The logic will only fail if you assume that 2025-12-31 and all subsequent dates are all equivalently forever.
Doing things that way means every time you check the value of a date, the very first check needs to be "is it the sentinel value?". But that's kind of the concept of a sentinel value anyway.
But there is something wrong with having some services actually end on 2025-12-31 and other services that are marked as ending on 2025-12-31 because they continue forever. Once 2025-12-31 is in the range of valid end dates, you can't tell the difference between the two.
> having a service begin on May 1st 2028 (2028-05-01) and continue until forever (2025-12-31).
That doesn't work as most of the program logic simple checks of a date is between two dates. It basically just treats 2025-12-31 as the end of all time. I suspect they will patch it before the end and change that date to something else.
Doing things that way means every time you check the value of a date, the very first check needs to be "is it the sentinel value?". But that's kind of the concept of a sentinel value anyway.