When creating a compound path (union) there are multiple duplicate nodes being created directly under other nodes.
In the video below there are 6 objects being joined. This creates 17 additional nodes as illustrated. 1 part gets 1 extra node, the next 2 nodes etc. This is only joining 6 objects, if you are creating a shape comprised of 60 objects or more this creates a huge number of extra nodes. If you need to remove all extraneous nodes before you submit an illustration this creates a huge amount of work!
This issue seems to be in all versions including the web version running in an incognito tab. I believe this is a relatively new issue. I’m using Windows 10 and the latest version of GD