Lower() scalar function working inconsistently on Cyrillic

[islombektoshev]

I was trying to match with LIKE operator using LOWER function, but I found out it is not wokring as I expected:

where is my test query

SELECT order_status, LCASE('Отменен'),  length(order_status)
FROM events
WHERE event_type='purchase'
GROUP BY order_status
ORDER BY order_status;

order_status	lower(order_status)	lower('Отменен')
(null)	(null)	отменен
В обработке	В обработке	отменен
В ожидании	В ожидании	отменен
Доставлен	Доставлен	отменен
К отмене	К отмене	отменен
Отгружен	Отгружен	отменен
Отменен	Отменен	отменен

Отменен starts with big letter and I have exact copy on database but it is not working on lower(order_status) but it is working on lower('Отменен')

Why this is happening, I suspect it might be FE and BE logic mismatch and How I can fix this on my Use Case