We may not call people QA, but in the end each person has different skills, and the same problem will arise inside developers.
Anyway, the same happens for any multi-phase cycle. Like with code review. When there are dependencies between people, you are going to need extra items to work on while waiting, and this fights with the requirement that everything should be done at the end of the SCRUM sprint.
There is no requirement that everything should be done at the end of the sprint.
Dedicated QA folk are redundant! The devs write automated tests for all the code they submit. It's 20 years since I spotted a dedicated QA person in the wild.