I've experienced this while leaving a different company that used a rare language.
It's a tough situation being experienced in <peculiar language for Company A> when you need to ace technical interviews in <mainstream language for Company B>.
Once you have a few years of promotions, it gets even tougher when you need to compete with <mainstream language> senior+ software engineer candidates at the destination company. Maybe <flashy brand name> was enough to land the interview, but experience mismatches and limitations can remain apparent in the interview itself.
It's a tough situation being experienced in <peculiar language for Company A> when you need to ace technical interviews in <mainstream language for Company B>.
Once you have a few years of promotions, it gets even tougher when you need to compete with <mainstream language> senior+ software engineer candidates at the destination company. Maybe <flashy brand name> was enough to land the interview, but experience mismatches and limitations can remain apparent in the interview itself.