Both Hive and POB pending rewards on a specific post/comment will be decreased in a proportion, how much voting power of Hive, AND POB the downvoting account have, how many tokens he has staked accordingly. If downvoter have staked some VYB, but zero POB staked, reduction will be applied only to HIVE rewards. The reduction of pending VYB rewards is never possible, technically, it is so by design of this token.
Both tags POB and VYB are general use tags, there are no specific rule when you can (or can not) to use them. Most authors always use them BOTH, in parallel.
Thanks so much for this clarification, it explains all I needed to know :) Saves me lots of time to search for it too!
I guess you'll be seeing more of my content, mainly (travel) photography.
With regards to finance & crypto, I don't consider myself successful enough to post on a regular basis :)