When you get tickets assigned to you, does it have all the requirements & acceptance criteria? I don't, and it's seriously difficult to know when you've finished a piece for work

No usually not. It is the source of quite a bit of misunderstanding but no one will take the time to do it.

Always look to have the upstream process fixed.
I am currently fixing a corporation with bad upstream data that is impacting downstream processes. Costing them time and money in bad data and decisions. Some of it just data validation and required fields. Low hanging fruit. Thoughts?

Not ever no