On-premises data gateway - file or assembly "Microsoft.Data.SqlClient, Version=1.13.20136.2..."

Hello,
since yesterday I have a problem with the data update in PowerBI. Locally in the DesktopApp everything works as usual, but online I see a warning message in the datasets.

The warning message says:

Unfortunately, a problem has occurred.

Could not connect to the datasource "undefined".
Try again later, or contact support. Provide the following details when contacting support.
Cluster-URIWABI-WEST-EUROPE-B-PRIMARY-redirect.analysis.windows.net

The data source is reachable, I see under Datasets, Gateway. Status is displayed in green.

The on-premises data gateway is running, current version 3000.72.6.

Have additionally looked in the logs from the gateway, in the GatewayErrors is the following entry, which seems strange to me:

Error reading data from provider:

"The file or assembly "Microsoft.Data.SqlClient, Version=1.13.20136.2, Culture=neutral, PublicKeyToken=....." or a dependency on it was not found.
The system cannot find the specified file."

Maybe someone had a similar problem and can give me a hint.

Thanks a lot,
Egon.