PHP：在某些情况下使用fgets函数破坏终端中的西里尔字符

Question

So, I tried to input cyrillic symbols to save them. I use fgets() function to get symbols (actually symfony console uses it). The problem is I can't prevent random corrupting of symbols when I get them. To simplify, I made the next code:

$i=0;
while ($i !== 100) {
    $i++;
    $str = fgets(STDIN, 4096);
    echo $str;
}
die;

I entered ТАйтл, Некоторый текст, Тайтл. Always on a first or second entering I got this wrong symbols. Example of wrong symbols: ðóððÉð╣Ðéð╗ (ТАйтл).

I tried to play with mb_convert_encoding, but generally, I always have UTF-8 encoding, so it's not about converting. But about in this case?

Many thanks for helping.