@Henning Møller , Thankyou for reaching out. based on the details shared, I checked the backend and it looks like the following tenant "483bc35e-31d9-46e7-bdf0-e9ce645b819c" is not available. Might be that the tenant is decommissioned. Please do check on the tenant details from your end as the error is popping up when you try to send the signout request with that tenant id, AAD, is not able to find that tenant and hence that error.
Hope this helps.
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