make everything UTC, people. It'll make your life way easier. Try it out.
That way you can merge them from different sources and sort them to help figure out interactions and causality. There might be clock drift from different sources but that's a much smaller problem than trying to eyeball multiple different logs concurrently, or write ad-hoc scripts to enable merging.
If you can’t go that far and still need local time zones in some specific part, just embrace your fate and keep and display timezones everywhere, even when it’s UTC.
TBH, I’ve never seen an organization that could 100% move everything to UTC. Especially with countries following DST and other shenanigans, and you want to quickly be able to compare events at the same local time.
If you're going to do it in storage, keep it outside the ISO/8601 string. Chronology is the most important thing to get right. Locality comes after
Unless the whole world agrees to communicate times in UTC, at some point, you will share a screenshot or a log message with someone outside of your company, and they cannot assume what time zone it's in.
When people try to apply this to other time related info, it's always a disaster.