Quote Originally Posted by E’Tallitnics View Post
A99: Yes. “Unless a feature that grants you temporary hit points has a duration, they last until they're depleted or you finish a long rest.”
There is nothing in the Spirit Totem description or Bear Spirit that states the TEMP HP granted only last while you are in the aura or while the Spirit Totem is present - therefore the TEMP HP follow the above "they last until they're depleted or you finish a long rest."

"Each creature of your choice in the aura when the spirit appears gains temporary hit points equal to 5+ your druid level." - no specific rule that over-rules the general rule to create a shorter duration than normal.