How to deal with a GM who favors other players

I have seen plenty of GMs write about how to deal with problem players, and I suppose I should ask about a GM who favors some players over others.

It’s only natural if you have a more rich backstory to get favored as a character, especially if your character is more chaotic and causes more problems, but the problem and chaotic character of our group tends to get the most attention, the most development, and solo sessions on their mission after splitting from the group. The GM is happy to play solo sessions with them, and have multiple conversations with NPCs for long stretches of time while the rest of us sleep or are left unaware. The character is always targeted by enemies, gets weapon upgrades and spell upgrades, and has the most development overall.

I have talked to my GM about this, who dismissed my concerns. I have also talked to the player about this, who apologized, and then continued. I know I am not the only one who feels this way, but the thing is that my concerns get brushed off as complaining for complaining’s sake. The most frustrating part is getting told to be more considerate of other players whenever my character causes conflict. It just feels like favoritism, and I don’t know how to deal with it besides just grinning and bearing it.