Briefly:
New zone for Aysén Region in Chile which moves from -04/-03 to -03.
Changes to future timestamps
Chile's Aysén Region moves from -04/-03 to -03 year-round, joining
Magallanes Region. The region will not change its clocks on
2025-04-05 at 24:00, diverging from America/Santiago and creating a
new zone America/Coyhaique. (Thanks to Yonathan Dossow.) Model
this as a change to standard offset effective 2025-03-20.
It looks like the timezone is available in the timeZones.txt export, but not for all geonames that have the Aysen region as their ADM1.
Also the timezone webservice does not return the America/Coyhaique timezone for coordinates in the Aysen region.