The str_replace function cuts Cyrillic. How to fix?

Question

PHP

On the local server, when calling the str_replace function, there are no problems; on the production server, the Cyrillic alphabet disappears from the final string. Someone faced a similar problem? Tell me how to fix it? iconv doesn't help. Transfers were made by Unix (LF) everywhere and did not help either

Answer 1

if you explain it in a simple way: the problem is in the difference between the encoding of the code and the lines
that come from the side (db/scraping/http requests/etc).
accordingly, they must be brought to the same denominator.
example script in UTF-8 and string in WIN-1251.

Answer 2

mb_ereg_replace
php.net/manual/en/function.mb-ereg-replace.php