Battery capacity dropped to 88 percent

good day. My name is Svetoslav. I am writing to you about the iPhone 11, which I have the battery capacity for a year and a few months ago it dropped to 87 percent bought by the operator Vivacom. so far I have used several iPhones and the percentages of capacity have not dropped like that. I want to do something about it if you please. It is not normal for it to fall so fast. I had an iPhone SE, I used it for almost 4 years and in the second year it was 88 percent. now i'm not happy how it fell so fast on iphone 11

[Edited by Moderator]