After recent upgrade my iPhone 11 just dying when fully charged

After the recent upgrade my iPhone 11 is just randomly dying. Only just 5 mins ago it just went dead. It was fully charged with a new battery July 2024. If I spot it I switch on but it goes to 10% battery but often will go dead unless I plug it in. I am a carer and need to trust my iPhone but no longer have faith in it. I have seen it go dead in middle of night despite been plugged in to charge. Can someone help thank you