power automate – GetItems on calendar fails with strange error about missing property or parameter

I get a strange error when requesting data from a sharepoint calendar using the GetItems operation in PowerAutomate.
It says:

Die API “sharepointonline” hat eine ungültige Antwort für
Workflowvorgang “Sifu-Anwesenheiten_abrufen_2” vom Typ
“OpenApiConnection” zurückgegeben. Fehlerdetails: “Im API-Vorgang
“GetItems” fehlt die erforderliche Eigenschaft
“body/value/17/EndDate”.”

(sorry, don’t know, how to retrieve the original message in English) It claims that the API-Call “GetItems” lacks a mandatory field/property/parameter named “body/value/17/EndDate”.

I do not understand why the field EndDate should be an issue here. I’m basically requesting the contents of this calendar. It should not be necessary to supply any additional information. To be precise I request the items with an ODATA-Filter applied. I use

EventDate eq 'Today-7days'

To retrieve all calendar entries newer than a week ago. So out of curiosity, I removed the OData-Filter an tried again. Now the message has changed:

Die API “sharepointonline” hat eine ungültige Antwort für
Workflowvorgang “Sifu-Anwesenheiten_abrufen_2” vom Typ
“OpenApiConnection” zurückgegeben. Fehlerdetails: “Im API-Vorgang
“GetItems” fehlt die erforderliche Eigenschaft “body/value/3/Title”.”

Now having removed the filter it claims about anothe missing parameter or so. I don’t know, what this could mean, because GetItems has not much parameters to supply, except the Odata-filtering field.

Update
I managed to retrieve the error message in English:

The API ‘sharepointonline’ returned an invalid response for workflow
operation ‘Sifu-Anwesenheiten_abrufen_2’ of type ‘OpenApiConnection’.
Error details: ‘The API operation ‘GetItems’ is missing required
property ‘body/value/3/Title’.’