Constant END_OF_SERVICE_ESTIMATE_SAFETY_MARGIN 

const END_OF_SERVICE_ESTIMATE_SAFETY_MARGIN: i64 = _; // 86_400i64

The number of seconds subtracted from the end_of_service.estimated_time reported by getdeprecationinfo.

Block times vary, so the halt can happen earlier than a spacing-based estimate. Reporting the estimate a day early gives consumers time to act before the actual halt.