Query parameters should not be set by the user but defined by the relying party, which in this case is ArcGIS, so when configuring the ArcGIS openID configuration, query parameters should not be used when setting the logout URL. Query parameters for OpenID Connect logouts are limited to the predefined set documented in the OpenID Connect specification:
https://openid.net/specs/openid-connect-rpinitiated-1_0.html#RPLogout
The guide for configuring AWS Cognito on Github has been replaced since the previous one, published four years ago, was obsolete and contained an incorrect logout URL.
https://github.com/Esri/idp/blob/main/Documentation/OpenID/AWS%20Cognito.md