My account has been suspended wrongly please help me.

Somebody may have reported your post and there's hasn't. Somebody may have reported them as well and they have received bans at this point also.

The filter doesn't always catch inappropriate posts. It's up to people to read the Community Standards and follow them.

if you look on the group posts for rocket league tell me why I got banned compared to them… why didn’t the group post tell me I had “inappropriate content” in my post?

If the enforcement tram upheld their decision, all you can do is wait out the suspension. LFG posts are only for looking for others to play a game with. Offering to buy/sell/trade,etc. is not allowed on them.

To enquire about bans you will have to post here:

forums.xbox.com/.../41.aspx

Account security on your console is your responsibility regardless of who made the improper modifications. These types of suspensions usually only last between 48 hours and 2 weeks but can be permanent depending on the severity of the offense and how many
times your account has incurred enforcement actions.

The forum that Maxen13 linked you to will be able to tell you exactly why and for how long the suspension is for.