Text Message Badge Won't Go Away on Mac

I have Messages syncing over the iCloud. When a message arrives, it is shown correctly both on my iPhone, iPad and Mac. The corresponding icon on all devices also shows a badge with the correct number of messages. When I read the messages on the iPhone, the message icon badge disappears on the iOS devices but stubbornly stays on the Mac.

After wasting a lot of time searching for a solution and trying a lot of remedies suggested in a lot of discussions also on this forum, the badge still refused to go away.

Then I stumbled upon this article from May 2018. Basically, the solution is this: I sent another message to myself from my Mac, and then read it on my iPhone. The badge now disappeared in both iOS and macOS.

Seriously, Apple? Not able to eliminate this bug in the last 5 years?