I dont think you can express Wireguard's battery usage by that %.
Imagine these 2 use cases:
#1. You do not use/touch your iPhone for 24 hours. Wireguard will now show 40% of the total battery that was used.
#2. You play the game Tetris for 24 hours. Wireguard will now show less than 1% of the total battery that was used. Because Tetris used the other 99,9%.
Imagine these 2 use cases:
#1. You do not use/touch your iPhone for 24 hours. Wireguard will now show 40% of the total battery that was used.
#2. You play the game Tetris for 24 hours. Wireguard will now show less than 1% of the total battery that was used. Because Tetris used the other 99,9%.