This likely has nothing to do with GrapheneOS, but rather with the modem in this phone. When I use WiFi, it's all perfectly normal. But the moment I run the phone over the regular modem connection (doesn't matter if it's LTE or 5G), it gets hot and just burns through the battery. Easily a couple of battery percentage gone every hour, passively. Could it be that this phone's modem is just incredibly inefficient? Is it perhaps certain frequencies (meaning certain carriers / countries), where this problem exists?