Apple Watch series 7 45mm GPS battery performance

I just got an Apple Watch. It is a series 7 45mm meter gps and its battery health is 100%. I used it continuously for fifteen hours today. During that time I made two or three calls and used Siri and all the features of the device were activated during these 15 hours.I observed the battery drain today. According to those observations, the battery was drained as follows.

AM 6:20      100%

AM 10.20.     76%

AM 11.20        60%

PM 12.20       52%

PM 1.20         47%

PM 2.20        40%

PM 3.20        32%

PM 4.20        26%

PM 5.20        20%

PM 6.20       16%

PM 7.20        14%

PM 8.20        7%

PM 9.20        3%

Considering the way the battery is drained, is there a problem with the battery of this watch or is it normal?

Many people say that an Apple Watch can be used for two or one and a half days. Even though I bought a new watch, I could only use it for 15 hours. Is there a problem with my watch?

The wallpaper I use for the watch is attached below.