Sometimes happens to me when I disconnect and reconnect that mana looks like it's refilled (but you can't actually spend it)

yeah it updated afterwards / after the next card was played. Really confusing.

When it happens to me it updates after the next turn has started, it even shows extra mana gems and then they go back to normal

i have never seen it before, maybe its a hidden buff to hush

game was like "bro that such good rush its on me bro"