As of 2023 most of Mexico is no longer observing Daylight Saving Time. Exceptions are Mexican cities that border US cities. Most JyotishTools apps did not require an update for this. JyotishTools, Tropical Skies and QuickJyotish for Android get the timezone data updated from the minor updates to Android devices. JyotishTools Pro uses a plugin that occasionally needs updating. In this case by accident the Windows version did get the update last fall. However the Android and iOS versions did require the plugin update.
Of course this won’t matter unless you are doing a horoscope for a new born this past summer. Mexico City which during DST would be 5 hours behind UTC or W5:00. Now without DST it will remain at the W6:00.
Why did Mexico do this? Not surprising because most all countries in the tropicals like Mexico don’t observe DST because the sun doesn’t really move that much compared to winter. On the other hand, Alaska gets 30 days of darkness during winter due to the sun being so far south and 30 days without nights during summer.
At that DST is kind of a psychological and mechanical distinction. Here in California, the citizens passed an initiative to observe DST year round. Why? Many of these folks like the extra hour of sunlight after getting off work. But then parents object to sending their kids to school dark mornings during winter. At that, congress has to approve this which is doubtful. And I’ve always said that in the Internet age we don’t need timezones anymore. All times would be UTC. That would be a real boon for astrologers!
Now about Tijuana. It borders the US city of San Diego which uses Pacific Daylight Time in the summer so Tijuana observes that. Here’s a handy website that shows a map of border cities using the neighboring US city timezone.
https://daylight-savings.com/zones/usa-mx-border-cities/
One additional note is the Online Horoscope here gets the timezone data from the host server. Strangely the web host did not update that. Inquiring with their support I learned I needed to update the PHP version to get the latest timezone database (PHP is a script language used for certain website functions not available in HTML or Javascript). I found that odd because on this computer which is Linux and has the same PHP version that this site was using at the time and has the new database. However bumping PHP to the newest version solved the problem for the online horoscope here.