OnePlus users beware: WhatsApp will (probably) drain your battery.
According to posts on Reddit and the OnePlus official forums, the latest version of WhatsApp (v.2.19.308, which dropped at the end of last month) is seriously eating into the battery life of a whole range of OnePlus phones, including the OnePlus 7T series that only arrived in October. The issue is affecting devices running either Android 9 or 10 and those hit by it are seeing up to 50 per cent of their battery life being consumed by WhatsApp, even overnight.
Users have found various workarounds for fixing something the developers should really have caught before releasing the app into the wild, including force-stopping WhatsApp when it's not being used. This admittedly defeats the purpose of the always-on messaging app WhatsApp is supposed to be, but at least stops it from killing your battery overnight.
The problem seems to have been fixed in the latest version of WhatsApp (v.2.19.325), which hasn't yet hit the Google Play Store, but you can download it direct from WhatsApp if you're one of those affected. [Trusted Reviews and Android Authority]