Most developers are basically powerless here, they use the standard libraries for time provided by their language, and those have to deal with what they get from the kernel. There's nothing they can do about timestamps in the filesystem.

For anyone designing new systems that store or transmit time, you should be aware of TAI64. https://cr.yp.to/libtai/tai64.html

Unless you are dealing with scheduling, or generating events with a particular cadence (e.g. daily, weekly, monthly) there is no reason to include UTC or time zones in your data model. They are view only concepts, with conversion to the local display format happening from TAI64 on the way out.