Microflow filtering runs in Java, which doesn't know about Turkish characters by default. You just need to tell Java explicitly to use Turkish locale when comparing strings.
Name it NormalizeturkishText with:
String inputTextString
import java.util.Locale;
public String executeAction() {
if (inputText == null) return "";
return inputText.toLowerCase(new Locale("tr", "TR"));
}
Before comparing/filtering, normalize both the stored value and the search input:
[NormalizeTurkishText(Name) = NormalizeTurkishText($SearchText)]