Hi Maran thanks,
I checked my problem again,
It was probably because of my database(postgresql) keeps these "Ş" character in different code
Here is the generated odata query when i am typing "DİŞ" to filter;
(startswith(tolower(Kod),'d%C4%B0%C5%9E'))
When i am typeing "Dİ"
(startswith(tolower(Kod),'d%C4%B0')
When i am typeing "Dİ
ş"
Its working again;
(startswith(tolower(Ad),'d%C4%B0%C5%9F')
So i have problem with
%C5%9E = "Ş" character on database side i guess