This is related to bug 61737.
Can we find out how many thanks are not being completed on desktop? That is, the user clicks on a thank button, but does not click on the confirmation button.
Does the level of non-completion differ by user experience level (perhaps total number of edits, or perhaps total number of completed thanks)?
The ultimate question is whether the confirmation step is likely to be preventing misclicks/unwanted thanks, or if it is mostly stopping wanted thanks. If it stops very few wanted thanks, then it might make sense to duplicate this confirmation step on mobile.