The link is to an image of the Arctype newsletter I received. I apologize for not having a better source. I couldn't find an online version of the newsletter, or any news sources that covered the end-of-life announcement.
If you go to the Arctype website (https://arctype.com/) you can see that you can no longer download the app, and you see an announcement banner at top that they are joining ClickHouse.
I am personally pretty sad that development won't continue on the Arctype SQL Client, as it is the primary client I currently use.