Win Update KB5004476, issued June 11, 2021 is intended to fix Gaming Services errors.
“Trying to play Flight Simulator. It wants to update Game Services in the Microsoft Store. It keeps failing,” one user wrote in the Feedback Hub. “Attempting to install Gaming Services, gets to the end (after restoring user settings) and gives me this error code (0x80073D26), another said reported the problem and Microsoft later said it’s investigating the reports.”
See the article HERE