Please note the double quotation marks I used. There was some reason for that.
Also, not a misinformation. Nevalistis had said that she don’t want to post on Friday but she couldn’t post earlier. It was a long time ago, I’m not bother to find that post.
In addition, S12 was 3 years ago. It is not relevant at all.
These were the season blog posting date for S16-S21:
Season 21 Ending and Season 22 Starting splashes are only showing if you have the launcher set to English (US), Portuguese or Spanish (Latin America).
If the launcher is set to German, English (UK), Spanish (EU), French, Italian, Polish or Russian neither of those splashes are present.
In other words, the launcher only informs you of the current season ending today, and when the next season starts, if your launcher is set to a language that is used for the Americas region. There’s literally no announcement for Europe and, until BouBou cross-posted it, there was no announcement on the EU forums either.
Blizzard not bothering to announce things like season start and end dates to an entire continent, either on their launcher or their EU forums, and those of us that reside in that continent pointing it out is not pedantry.