Forum Bug? What is the Vilnius tag and why does it automatically get added?

I posted a thread on a So-Called Dollar and the "Vilnius" tag is automatically added. I can't get rid of it, even if I remove all tags.
The closest thing I found is that it's the name of a Coin Expo:
MS International Coin Fair Vilnius 2018
Anyone know why this tag is automatically added?
Is this a forum bug?
PS: It's interesting that this post doesn't have that tag auto-added.
Tagged:
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Comments
Interesting. I have seen those types of tags but assumed the poster added them.
Odd. Vilnius is the capital of Lithuania. Have no idea why it would be attached to your post.
Jim
When a man who is honestly mistaken hears the truth, he will either quit being mistaken or cease to be honest....Abraham Lincoln
Patriotism is supporting your country all the time, and your government when it deserves it.
The forum software knows something you don’t know...
TurtleCat Gold Dollars
It's part of the new AI engine in play.
Vilnius was a second century Roman store owner in the province of Macedonia who, rather than using coinage, would return "change" to his customers with tokens he issued without the approval of the Emperor, Antoninus Pius. He was jailed and later ridiculed publicly for his love of tokens over provincial coinage.
So ... looks like the AI has figured out your great affection for and knowledge of exonumia.
See http://www.doubledimes.com for a free online reference for US twenty-cent pieces