Android bugs go to the maintainers of that specific device or of the custom ROM installed on it.
Using the unaltered version that was installed on the device when you bought it? Reports go to the manufacturer usually.
Unless it’s a carrier branded version, like a Verizon or Tracfone provided phone, in which case bug reports go to them. But frankly, don’t bother, and for the love of all things holy spend a little more money and stop buying carrier branded phones.
For custom ROMs, bug reports go to wherever the maintainers of that ROM ask bug reports be submitted. Usually Git, XDA forums, their website, or their Discord/Telegram channel. And fuck that last one, because hiding bug reports and other information in non-indexed places like Discord is making this more difficult for everyone.