Query string accent encoding issue between JS and vb.net

The problem

When I try to retrieve the query string parameter the accent decoding doesn’t work correctly.

Environment & info

Website html/js and server side .net Framework 4.0 (written in vb)
I don’t have access to the server, and therefore not even to IIS
In the web.config I set the encoding to UTF-8: <globalization uiCulture="it" culture="it-IT" requestEncoding="utf-8" responseEncoding="utf-8"/>
I’m quite convinced that this problem wasn’t there until a few days (months?) ago.
I can’t provide the site to check the problem on.

Code & test

$txtSearchSimple.val() is an input/textbox that contains: “perchè questo”

//JS
console.log(encodeURIComponent($txtSearchSimple.val()));
window.location = '/page.aspx?t=' + encodeURIComponent($txtSearchSimple.val());

In console the browser write correctly: perch%C3%A8%20questo

But on VB:

Session("TEST_Acc") = Request.QueryString("t") & " --> "
Session("TEST_Acc") &= Uri.UnescapeDataString(Request.QueryString("t")) & " -> " 
Session("TEST_Acc") &= HttpUtility.UrlDecode(Request.QueryString("t")) & " -> " 
Session("TEST_Acc") &= HttpUtility.UrlDecode(Request.QueryString("t")) & " -> " 
Session("TEST_Acc") &= HttpUtility.UrlDecode(Request.QueryString("t"), Encoding.UTF8) & " -> " 
Session("TEST_Acc") &= HttpUtility.UrlDecode(Uri.UnescapeDataString(Request.QueryString("t")), Encoding.UTF8)

Session("TEST_Acc2") = HttpUtility.UrlDecode(Uri.UnescapeDataString("perch%C3%A8%20questo"), Encoding.UTF8) & " -> " 
Session("TEST_Acc2") &= HttpUtility.UrlDecode(Uri.UnescapeDataString("perchè questo"), Encoding.UTF8)

The results:

'TEST_Acc:
perchÃ¨ questo --> perchÃ¨ questo -> perchÃ¨ questo -> perchÃ¨ questo -> perchÃ¨ questo

'TEST_Acc2:
perchè questo -> perchè questo

I also attach the result of the chrome request/response

I don’t understand how it is possible that between the request (which seems correct) and the server-side fetch it is decoded incorrectly even before I can query the value with the Request.QueryString.

Thank you very much for the help you want to give me.