Battery issues - Health stuck at 100%

I got my Iphone 7’s battery replaced about 7mo ago, as I cracked the screen, and the guy said it was only really worth his time to do both, plus I needed it anyways (Bought this phone refurbed) This was all before I had ever taken apart a phone, now I have. I feel like I should replace it, as the battery health is stuck at 100%, 3utools doesnt give me a health or a manufacturer either. I wonder if this is a bad battery, and if I should replace. The battery life has been not great, I now have to charge it 2x a day, after the IOS 14 update. Is this battery bad, and should I replace it? Would this fix the many crashes and freezes I have while using this phone? I suspect it may, but IDK. Thanks for your help!