AITA for this?

I'm washing the dishes 4 days a week on my fam's house. I know everybody here hates washing dishes on ur own fam's house bc for me the mess they make tells you they don't care, even pigs eat clean on their plate but not them.

Yesterday my grandma had a complications so my parent, older sibling and me are taking care of her while my younger sibling was woken up by the commotion and went back to sleep. (The younger sibling is already in their last Junior High so they have enough comprehension and responsibilities.)

I remembered the house was in a mess and that day was their turn to clean the dishes. I told them to get up bc it's their sched to wash and they didn't move. Not long after the commotion settled down and my older sibling washed their dishes. I go back to the bedroom (we share a room) I heard them punching the wall and murmuring so I know they were faking the sleep.

Next day I told them to wash the dishes for tomorrow bc our older sibling had to clean up their mess. They said that the older sibling already did their dishes so there's no need for them to wash for tomorrow. I was so angry I told them that it was their responsibility and to help while we were helping our grandmother when she was in critical condition.

Our parent was in the room and didn't say anything.... I told them about my younger sibling's chore responsibility WHICH our parent made a rule to HAVE EVERYONE in the house have one. OUR PARENT KEPT THEIR MOUTH SHUT AND I REALIZED. I'm being ignored aren't I? after all I did to follow all of your rules in the house yet you let the younger sibling do as they please while I get the end of the stick.

Multiple times I try to speak up about my younger sibling's behaviour to our parent they say "Leave your younger sibling alone." There was one instance that the younger sibling had a breakdown about their chore responsibilities, they were acting cringe like a chuunibyou like you see in tiktok cosplayers. Our parent said "What happened to them? they have gone crazy..." Maybe if you didn't spoil them so much and let them do whatever they want and tell your other children to leave them alone maybe they should know how to conceal their emotions like you other children do and don't make a deal about it.

I'm just tired of my parent and younger sibling.... If only the first day of school would come near and I'll leave those two and never come back home again.