Think it's a visual glitch in this one as it's happened to me a few times too.
You still have three crit buffs at the start (reflecting the damage from the charges normally there) and the damage output numbers should be on par with that.
This is an old bug that goes back over a year or two, but keeps resurfacing from time to time. Try to pay attention and notice it before you enter fights. Back out from fight menu/restart game.
Just dropped mine in war today, started fighting and after 20 hits the opponent was only down about 25% (domino) then I looked and realised no charges (had already gathered 3 before that fight) iPhone 8 iOS 14.6
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You still have three crit buffs at the start (reflecting the damage from the charges normally there) and the damage output numbers should be on par with that.
Corvus and pretty much everyone I didn't list above, still get all their benefits from their persistent charges.
If you want the icon back, if you notice they are missing, restart your game and they eventually come back after a few restarts.
iPhone 8 iOS 14.6