Thank you @shameemreza,
Disconnecting MC Google Account, etc and setting it up again resolved the syncing issue.
Before I saw your reply I used the following method to disconnect it (I suppose it works just like the approach you recommended): WP Admin > Marketing > Google Listings & Ads > Settings.?Click Disconnect all accounts.
And used the method to set it up again: ?Marketing > Google Listings & Ads?and set up the connection again.
The only problem was that some of the Google Merchant Center settings (e.g, Shipping) got reset to zero resulting in products disapproval and had to be set up again to get product approved again.