Errors with some services

Nobody has claimed this yet.

I have problems with some services - Google Photos, Google Drive (open a few directories down), Twitter and some others (I do not remember a full list).
It always says error is CORS, but I did a debug and the header seemed fine.
`Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource at
https://drivefrontend-pa.clients6.google.com/v1/sharedDrives:list?key=.... (Reason: CORS header ‘Access-Control-Allow-Origin’ missing). Status code: 400`

Google answers with 400 Bad Request!!!, same error sometimes appear when cookies are broken but cookies are
synchronized and this error still appears.

While debugging I thought I found the issue in this part (letter case can be different and origin will be there twice):

```
details.requestHeaders = details.requestHeaders.filter(requestHeader => {
return !header_keys_to_delete.includes(requestHeader.name);
});

// Add appended headers
details.requestHeaders = details.requestHeaders.concat(
headers_to_append
);
```

Changed it to:
```
details.requestHeaders = details.requestHeaders.filter((requestHeader) => {
return !header_keys_to_delete.includes(requestHeader.name);
});
for (const header of headers_to_append) {
const headerIndex = details.requestHeaders.findIndex(
(h) => h.name.toLowerCase() === header.name.toLowerCase(),
);

if (headerIndex !== -1) {
details.requestHeaders[headerIndex].value = header.value;
} else {
details.requestHeaders.push(header);
}
}
```

But it changed nothing.
Hope someone has an idea what's the root cause of the issue.

Start by reproducing the Google Photos, Google Drive, and Twitter failures, then inspect the request-header filtering and appending code shown in the issue. Compare the resulting headers and responses, and consider the issue complete when the affected service requests no longer fail with the reported CORS or 400 errors.

Written by the indexing model from the issue text.