That certainly shouldn't be happening. Have added additional hard checks for PM assets into CB Activity to prevent PM assets of any kind from being able to log activity regardless of where they come from. Please update to latest CB Activity build release and this will be fixed.
forge.joomlapolis.com/issues/9396
Your existing activity where this has happened will be suppressed with a "Something Went Wrong!" error and any notifications with a PM adjacent asset like for the activity will be suppressed as well. Future uploads will not create such activity at all.
We will work on releasing a stable minor release as well instead of just a build release.