The battery of MacBook Air 2020 i5

I acted my MacBook Air 2020 i5 in about September 2020; I didn't buy apple care and I know that the warranty period ended already, but the battery of this mac has some problems, at the day that I wrote this, the battery cycle is 142 and the battery life is 87%, I can only use it for 3 or 4 hours for JUST writing a document or reading a book, for example, my friends MacBook Air 2015 and my mac start using at the same time, and we are just reading, while he has 95% left, I only have about 80% left, when he reaches 86%, my mac drop to 65%, so I'm wondering what's going wrong with this mac, I charge it to 100% then unplug it every day, and I never put it to charge whole night or for a long time. So I want to ask will apple change my battery for FREE because of the battery's problem or do I have to pay for it just because the warranty period is over? No matter what. Thank you for reading this paragraph, and I will be more exciting if you can share similar things and what's the result if there is one.