Wired Carplay effect on Battery Health

Hello All. i just recently bought a car with wired Carplay. i am currently using Iphone XS Max which i bought for sometime ago. i was really careful with battery usage and before starting using Carplay my battery max capacity was 85%. however, although just for a week i am using my car, with carplay connected, not longer than daily 30 min usage, it seems my battery capacity dropped to 80%. i read a lot of entries and articles saying it shouldnt be the case, but since this is a real experience, i would like to ask you that if anyone else had the same problem?

thank you in advance