Cyrillic SQL problem

I am trying to search for a substring, but I have problems with Cyrillic.

select * from `posts` where "Текст" LIKE CONCAT("%", `substr_ru`, "%"); 

For some reason, this query displays to me absolutely all entries in which substr_ru is an empty string and completely ignores the contents of the "Text".

While with a Latin everything works without problems.

 select * from `posts` where "Text" LIKE CONCAT("%", `substr_en`, "%"); 

Exactly the same behavior is observed with the functions instr and position . Cyrillic works adequately with other operators, for example:

 select * from `posts` where "Текст" = substr_ru;