> Why? Because perhaps in 2030 Russia has taken over Dnipro and moved it from Europe/Kyiv to Europe/Moscow.

Not that in invalidates your overall point, but in that case the TZ database would create a new timezone (eg. named Europe/Dnipro) to reflect that from 1996 to 2030 it was UTC+2/UTC+3 (with EU DST rules); then switched to UTC+3 only.

This reflects that there is a place whose rules changed on 2030. Places don't move to an other existing timezone because that would prevent reasoning about past datetimes.

Good point. As you mention, that doesn’t matter in this case, as even if a new named time zone is added, the stored named time zone would’ve been written before Europe/Dnipro was created (in case anyone’s wondering why this doesn’t invalidate the point).

How do the time databases handle location renaming (eg in 2030, Dnipro becomes Putinville?