Why did strawberry write to tag "Lyrics-xxx"?

[mtfurlan]

Really weird thing just happened, I used the edit track information lyrics tab to save lyrics for a song.
It showed up in the tag "Lyrics-xxx" instead of "Lyrics"

A random website suggests it's attempting to put a language tag in maybe?
I'm not finding much information because google has other meanings for "xxx"...

Why did strawberry write to it?
How do I make strawberry never write to anything besides "Lyrics" ever again?