Missing Apple Watch not on find my app

So I misplaced or lost my Apple Watch (series 8). I can’t find my Apple Watch anywhere in my house. I went on the find my app and it’s not there for me to track or lock it as missing. I checked my sisters watch because I connected it to her phone, it’s on her find my app (even if the watch has been erased). I haven’t connected it to my phone to test if that would be the same result. Im not sure if it’s because after some time of it being dead the watch disappeared since it’s not not on or connected to bluetooth or it has been paired to another phone. I asked some people land they’re giving me the option that maybe someone took it or that the battery has been drained and the watch has been offline for sometime

Has anyone else experienced losing their watch and not it being on their find my app.