Have heard of a pilot who failed the captains' exam twice and became a senior first officer. He has an extensive flying experience, longer on type than most, and is teamed up with freshly graduated captains. Last I heard, pay was good.
It is some years ago, before covid and at the time of severe pilot shortage worldwide, and at the time after two attempts there were no more opportunities to graduate to captain. The choice was to remain senior first officer at the airline or leave for another and go for captain there.
This is a single case that I've heard of and I do not want to make the suggestion that this is always the case. It is essential for airlines to be able to couple experienced captains with novice first officers and vice versa, senior first officers simply have an essential role to play.