Scrum teams need to spend part of their time during the current sprint looking forward to the next few sprints by grooming the backlog. Grooming the backlog includes activities such as meeting with the product owner to discuss the upcoming features to better understand them and doing research spikes, if needed, to understand the complexity of the features.
If your teams are focused solely on the current sprint, unless you are building very simple well understood features you will start to see the teams fail to meet the commitments they make during Sprint planning.
Also you will start to hear statements like these:
“The product owner should have told us this feature was so complex.”
“The product owner did not describe the feature properly.”
“No one told us that this feature would require a major change to our batch system.”
While there will always be some level of discovery during the sprint, spending time properly grooming the backlog and researching the features should keep your teams from having major surprises during the sprint that lead to failed commitments. While this will take time away from implementing the current features, it will be time well spent.