Although Wacom hardware should have no reason for sending out the history of application use of its owners, it looks like this has been happening for a while and there's no official explanation for that yet. Nevertheless, this story is quite intriguing and worth keeping an eye on.
https://www.notebookcheck.net/Another-one-caught-red-handed-Wacom-has-been-tracking-your-activity-as-well.453105.0.html
There's also an "Epilogue" section in that linked article which says that the Wacom driver/software is no longer doing it, so I wonder if it was some code screw-up that got fixed, or Wacom feeling the heat from this story.
One thing to note is the date it got fixed, which predates most publications (yourselves included) and blogs picking up and echo-chambering this, so either someone close to Wacom (there's a "Rick" mentioned there) alerted them after finding the issue himself, or he found the story before the rest of you did.
If you go through it to the end you'll see that the driver was not doing it for a period, then it started again. Just go all the way to the end... Quote - "On February 3rd I checked in and was elated at what I saw: [image with code that mentions Rick]
I had no idea who Rick was, but I was glad he was back. Wacom were illegitimately siphoning off my personal data again, and I couldn't be happier. I grabbed some better screenshots, fixed some grammar, and hit publish. The rest is history."