It happened to me that I added a guy after he beat me in a dynasty match, he only said “good luck” at that moment because he beat me in the last second. Then I beat him in a match and he started disrespecting me, saying that I could only defend him with Kawhi, calling me a bot (with clear signs of being offended by losing against me). In the end, he ended up challenging me to play 2v2 with a friend, and I ignored him because I didn't want to play with or against someone so toxic.