In claimConcentratedRewards() and claimAmbientRewards(), the implementation takes an array of the weeks which are expected to be claimed. This is user input, and lacks any validation over the provided argument values.
Using claimConcentratedRewards() as the example, we can see each element in weeksToClaim is not checked to be an actual week, i.e. that week % WEEK == 0.
Consider adding an explicit check to ensure the elements in weeksToClaim are valid weeks.
