This happened because of the change in tracking that Google made in October 2018.
They have disabled tracking templates that GA Connector uses to add these UTM parameters (in order to enable parallel tracking).

Thankfully, Google Ads have another feature that allows adding UTM parameters. It’s called “Final URL Suffix”.
We are now using this feature to power another solution that allows us to tracks campaigns, ad groups and keywords.

In order to implement this solution, please you can disable the old version of the GA Connector script and then go through this instruction.