The bottom line is this:
Long term foreign residential rental real estate placed in service on or before Dec 31, 2017 is depreciated over 40 years.
Long term foreign residential rental real estate placed in service on or after Jan 1, 2018 is depreciated over 30 years.
The change took place with the Tax Cuts and Jobs Act of 2017 that was passed into law in January that same year. You can read it at https://www.govinfo.gov/content/pkg/BILLS-115hr1enr/pdf/BILLS-115hr1enr.pdf
