false modesty

A vain or hypocritical pretense of holding a low or humble opinion of oneself, one's abilities, or one's circumstance so as to encourage others to say the opposite. There's no need for that false modesty here; you are fully aware of your success and achievement, and you don't need me to reaffirm it for you. I find her false modesty quite unbecoming. Ugh, Jake is the king of false modesty! He always says self-deprecating things and then waits for us tell him he's wrong.

in all modesty

Without trying to boast, brag, or seem overly important. You asked me about my career, so I'm trying to speak in all modesty about the successes I've found. I talk about my career in all modesty because I know how much luck factors into longevity in this industry. A movie star talking about their success in all modesty? How novel!