maam I faced the same issue but on a different handset galaxy note9 but later realized it occured due to 3 causes.
1.use of phone cases causes heat up which drains the battery
2.on the contrary you can check the fact on internet that extreme cold also effects the battery drainage.
3.due to software issues excessive apps specially photo editing apps and long time phone usage without restarting.
4. I can give a solution but not sure whether it will work pls hard reboot your phone once it solves such issues even during hard reboot you can check the battery information
5. bonus point in this samsung members app you can also check your battery status
