In the classic interface, you were able to page between open records in a view by using the small up/down arrow in the upper-right corner of the record. At first glance, that feature is missing from the unified interface. Keep reading to see how Microsoft modified this feature in the new UI.
Upon opening the record, you can click on the small circled arrow, in the upper-left corner, adjacent to the “+ New” button. This expands a mini-version of the view you are working within, and you can select from within this list to quickly navigate between records:
Bonus tip–this also works with subgrids within a record! If you open a record in a subgrid and select this same arrow, the full list of records from the subgrid will be displayed.