As of April 2022, Google Ad Editor supports the creation and editing of Performance Max campaigns (version 2.0 and up).
This is all good and well, but there’s a sneaky little bug: if you copy-paste a PMax campaign that has Final URL expansion set to ‘Only send traffic to the URLs you’ve provided’, the copy will have this option set to the default ‘Send traffic to the most relevant URLs on your site’.
To fix this, you’ll need to go into the Google Ads interface and change this campaign setting manually.
H/T to Lyubomir Popov for pointing this out.
– Nils