Thank you very much for the reply Cold-Egg
Yes I have also used the checker that shows h3 supported, maybe because it has the header? (inspected first request in dev tools shows header with all the h3 values).
But in Chrome's dev tools network the index.html is transfered via h2 and not h3 (while the image is transfered via h3) both of them are stored in same folder.
Shouldn't index.html file have been transfered through h3? at least in others sites with h3 I can see the page request done through http/3