How to fix the encoding on the site?

Question

PHP

Russian letters 'I', 'E' in caps are perceived by the site as � (symbols)
What could be the problem? (all other letters are displayed as needed)
Information :
Data is taken from the GET request
UTF8 file encodings are set
Already the whole brain has broken ...

Answer 1

Before sending
$string = iconv("windows-1251", "utf-8", $string);