Major review for the second time
It is difficult to see what other alternative the editor has; given that problems were identified in the paper by the original reviewer, the editor need to be confident that these have been adequately addressed, and a good journal should not base their decisions on the view of a single reviewer.  I'd say it is perfectly normal, and beneficial.

If the second reviewer has identified further shortcomings in your work, while that it perhaps not what you were hoping for, but in the long run I suspect they have done you a favour as it will strengthen the paper that is finally published.  I wouldn't be too concerned by this, just address the new set of criticisms as well as you can and resubmit.

What is not really acceptable is for a reviewer to give one set of comments, which you then address, and then for the same reviewer to give another set of criticisms about the revised version that they could have made in their original review.  However as this is a new reviewer, I don't think there is a real problem.