Assalamu Alaikum, as we know it's even haram to say "Uff" to parents but what about step mom? Does this ruling also apply to her? I'm asking because I and her sometimes have heated loud arguments. Am I committing a grave majoring sinDo I HAVE to treat and respect her like my actual mother(NOTE:I met her when I was 9 and now I am 16 so she did not raise me as a baby

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

The status of the stepmother is not like that of the mother, and it is not obligatory that one shows her the same amount of respect and dutifulness as he would show his own mother. However, she is the father's wife, and being kind to her and treating her with kindness is righteousness and dutifulness to the father, as in the hadeeth: The Prophet said: “One of the best acts of dutifulness is a person’s good conduct towards the loved ones of his father.” One of the most significant types of kindness to parents is maintaining ties with their loved ones and being kind to them. The father (her husband) most likely wants her to be treated kindly, therefore, being kind to her is dutifulness to the father. Any disrespect towards her would have hurt your father, and hurting him is disobedience. Your righteousness and kindness to her do not require that she had raised you.

What you called heated and loud arguments, then if they hurt her, it is forbidden, and the one who does them is committing a sin. This is from the point of view of it causing harm, not because she is a stepmother, but because harming a Muslim is forbidden. At-Tirmidhi narrated on the authority of Ibn' Umar who said: “The Messenger of Allah ascended the Minbar and called out with a raised voice: ’O you who accepted Islam with his tongue, while faith has not reached his heart! Do not harm the Muslims, nor revile them, nor spy on them to expose their secrets. For indeed whoever tries to expose his Muslim brother’s secrets, Allah exposes his secrets wide open, even if he were in the depth of his house." If this applies to all Muslims, then how about the stepmother, especially if she is old?

Allah knows best.