When I try to create a screenshot this error appears in the chat:
"C:\Users\Татьяна(My cyrillic username)\AppData\Roaming\.minecraft\screenshots\<DATE>.png": Corrupt JPEG
(FILE 1)

Kinda suspicious because of my cyrillic username.

Done some testing (FILE 2):
Created a new user with latinic name "tyom", now screenshots work.
Yep, my suspections have confirmed.