Credentials for web conection are invalid (custom conector for sharepoint)

So, yeah, another one about sharepoint and credentials. I searched the forum and the web in the last two days and couldnt find anything that could help me.

I have a report that reads data from a SharePoint list, and the client asked me to add two pieces of information that I couldnt find using the connectors available in Power Query: the comments and versions of the items. So, I made two custom connectors using Web.Contents() and Relative Patch to get this information dynamically from this list.

The code is:

let
    CustomFunction = 
    ( List_SP as text, Item_ID as number ) => 
    let
        Source = 
        Xml.Tables(
            Web.Contents(
                SP,
                [RelativePath =  "/_api/web/Lists/getbytitle('" & List_SP & "')/items(" & Text.From(Item_ID) & ")/Comments()"]
                )
            ),
        Navigation = Source{0}[entry],
        Content = Table.SelectColumns(Navigation,{"content"}),
        ExpandContent = 
        Table.ExpandTableColumn(Content, "content", {"http://schemas.microsoft.com/ado/2007/08/dataservices/metadata"}, {"content"}),
        ExpandProprierties = Table.ExpandTableColumn(ExpandeContent, "content", {"properties"}, {"properties"}),
        ExpandSchema = Table.ExpandTableColumn(ExpandeProprierties, "properties", {"http://schemas.microsoft.com/ado/2007/08/dataservices"}, {"properties"})
    in
        ExpandSchema
in
    CustomFunction

NOTES:
- The SP in the web.contents first argument is a parameter that has the website address  (https://client.sharepoint.com/sites/SiteName).

- The other tables use the same parameter as source, but with the standard sharepoint connectors.
- The second function is the same, it only changes the last argument of the relative patch from Comments() to versions.

On the desktop everything works and updates, but in services, the credentials for the web connection are invalid, and I tested all possible combinations, whether or not I ignore the test connection, and nothing works, I receive code 400 with the message

and when i try to update the credentials, i receive the message

Ive already tried deleting and publish again the semantic model, changing the privacy levels in the desktop file (combine or ignore), and nothing works.

So, what am I doing wrong or not seeing?

Thanks for the support