Testers should not estimate effort only for themselves, but rather they should collaborate with the other members of the team to estimate the effort required to complete a user story. The effort estimate should take into account the testing effort as well as the effort required for development, analysis, and any other tasks that will be required to complete the story.
When a story is technically challenging but relatively easy to test, it would typically be voted with a high vote. This is because while the implementation of the story may require a significant amount of effort, the testing of the story will likely not be as time-consuming.
On the other hand, if a story is easy to implement but complex to test, the tester may vote with a higher number than the developer and analyst. However, the final vote would depend on the team's consensus, as each member's perspective and expertise is important for determining the effort required for the story. Ultimately, the team should come to an agreement on the final vote, taking into account all the perspectives and expertise in the team.