MacBook mid2012 shutting down while in sleep after battery replacemen

Specs: Macbook Pro Mid-2012, running 10.15.5, 2.5 GHz dual core i5, 16GB RAM

My old battery started going out last July (2020) to the point my computer would shut off immediately if power supply was unplugged. I replaced it with the appropriate battery (ordered from ifixit), installed it, ran through the power calibration, and it worked fine for about 3-4 days.

I have the power settings set to sleep after 20 minutes with power supply and battery. When the laptop goes into sleep mode it will stay that way sometimes for hours, but will inevitably shut down on its own, even when the power supply is plugged in. Sometimes it will restart on its own after a couple hours, sometimes I restart it manually. Every time the battery has drained, sometimes as low as 50%. I have to unplug the power supply and plug it back in for the battery to start charging again. I also get an error on restart that says the computer restarted because of a problem, but I can’t really interpret the error report, but it has something to do with sleep mode.

I can unplug the power supply and the laptop stays on and the batter drains normally, but I can’t figure out what’s up with this random shutting down. The batter status is showing as normal, it charges fine, it runs fine on battery power, and there are no scheduled restart settings. Any help is greatly appreciated!