What is the Sheikah Slate update you get from Symin?

Solution 1:

If I'm understanding your situation correctly, what you're talking about isn't actually an upgrade.

What was downloaded was a new entry for your Hyrule Compendium. Take another look at it - there should be a picture inside there somewhere that you didn't actually take.

From now on, you have the ability to unlock as many pictures for the Hyrule Compendium as you want, just by talking to Symin. It will randomly add pictures of things you haven't found yet. The only downside is that you'll have to pay 100 rupees for every single one. It's basically just an alternative way to fill up your compendium if you have a lot of cash and don't feel like going around taking pictures all the time.