Be sure to let your battery deplete completely from time to time, as the battery gauge seems to be misalligned a bit!
I've installed AccuBattery Pro on my ZenFone 8 just like on any of my Android devices, and when it had 2% left (which seems to be scary, isn't it?), I've decided to let it run completely out of juice, so I've started YouTube, and when the battery was on 1%, that 1% meant another 100+ minutes of video watching, and another 500mAh of battery, which wasn't present by default.
Now I have over 3.600mAh of battery in my ZF8 according to AccuBattery, but most probably it will take another few rounds to "format" the battery and recalibrate it.
Having the battery mode on "Durable" also can help to prolong battery life, of course.
So far so good, I love my ZF8, it's everything I wanted after carrying my SIM card in my Unihertz Jelly 2, and carrying my ROG Phone 3 with me to be able to use WhatsApp for a longer time...