When I share an item/doc in DT to Apple Reminders, the item link is added. When I share it in DTTG, a file link (file:///private/var/mobile/Containers/…) is added instead. But, the file link cannot be opened.
You can get the same result as DT in DTTG but you have to use the iOS Shortcut and extract the link and format it within the shortcut
I have a complicated shortcut that creates a group structure in DTTG and then links the main doc in the group to a reminder. It matches a script I have that does the exact same thing in DT.
I can see a grim workaround but it would be better if it worked. In the meantime, I have a “copy item link” option on my share sheet. If I click that first, I get a message saying the item link is copied. Then if I click the share sheet again and click Reminders, I can now paste the item link in the Notes before clicking “Add”. It only adds an extra few seconds to the process, but you’d need to remember to grab the link first.