The sunrise/sunset times that you see in the IDE when looking at a location are accessible by Groovy SmartApps, predominantly used by Smart Lighting. Those values updating is dependent on the Groovy SmartApp “Weather Station”. Long time users might see that SmartApp installed under “Hello Home” which is where Routines from the Classic app were also nested. The sunrise/sunset values are updated twice a day. For example when a sunset event executes tonight (3/4), tomorrow’s (3/5) sunset event will be scheduled.
As part of the Classic app retirement, starting a year or so ago, Hello Home and therefore Routines and the Weather Station stopped being installed when a location was created. As Smart Lighting has not been retired this created an issue with sunrise/sunset events and Smart Lighting automations. To work around this, when a sunrise/sunset automation is added in Smart Lighting there is a check to see that Weather Station is installed and if not, it is installed. Note, Smart Lighting isn’t available in all countries/regions. Custom automations should cover the same use cases but if you find something you can do with Smart Lighting but not a custom automation, please let support know so we can work to address feature parity.
While not a publicly documented endpoint and subject to change, currently sunrise/sunset times used by custom automations can be viewed via https://api.smartthings.com/services/coordinate/locations/LOCATIONID/capabilities?name=weather as described by @orangebucket: Is there a way to see what you sunrise/sunset times actually are? - #17 by orangebucket
These values are also dependent on the geocoordinates set in the mobile app. They pull from a different source than Weather Station so there might be slight variation between the two. It is also worth noting that sunrise/sunset events for custom automations are typically rescheduled every few days as sunrise/sunset naturally drift earlier or later, depending on the time of year and your location on the globe. If you are seeing sunrise/sunset events trigger at the exact same time for a week or more, such as the current situation we are seeing, you should contact support.
As an additional note, daylight savings time will be starting soon and some users may see sunrise/sunset events misfire by an hour. In my experience this seems to only impact some users of the legacy Weather Station and usually only when there is a time offset. If there is a misfire, sunrise/sunset should reschedule correctly the next day. If you are seeing multiple days of incorrectly firing sunrise/sunset events, please let support know. Also I can’t promise but would would expect the sunrise/sunset issue impacting custom automations to be resolved prior to DST so you may choose to move away from Smart Lighting ahead of that if you have concerns.
Example of sunrise/sunset from weather capability endpoint: