lose your touch
US /luːz jʊər tʌtʃ/
UK /luːz jʊər tʌtʃ/

1.
腕が落ちる, 勘が鈍る
to no longer be able to do something well that you were previously good at
:
•
The chef used to be amazing, but he seems to have lost his touch lately.
そのシェフは以前は素晴らしかったが、最近は腕が落ちたようだ。
•
After not playing for years, I've really lost my touch at tennis.
何年もプレイしなかったので、テニスで本当に腕が落ちた。