הלכה על ראש השנה 31:9

On weekdays, one must not interrupt between Ga’al Yisrael and the Amida for any davar she-bikdusha, for adjoining redemption to prayer helps save people from distress. However, on Shabbat, which is not considered a day of distress, there is less of a necessity to adjoin redemption to prayer, and according to most poskim one may interrupt to respond to devarim she-bikdusha. On festivals, which are days of judgment (on Sukkot, we are judged regarding water, on Pesaḥ regarding the harvest, and on Shavuot regarding tree fruits – see RH 16a), one may not interrupt between redemption and prayer (SA 66:9; Rema 111:1; Peninei Halakha: Prayer, ch. 16 n. 7).