I’m not familiar with WOO yet and just installed it. So, you right, there are both Belarusian rubles in drop down menu. But with the “new ruble” there are still Br on the product page:
View post on imgur.com
I appreciate github link, and I see BYN there, but how can I use it? All that i found at that time is that I should use additional code in functions.php, better in child theme:
https://docs.woocommerce.com/document/change-a-currency-symbol/
If it only one option, i will do it.