The great memoriser adh-Dhahabī (رَحِمَهُ ٱللّٰهُ) said,

“The speech (criticism) of the pious critics (scholars of jarḥ & taʾdīl) about the weak (narrators, callers) is from advice for the sake of Allāh’s religion and a defense of the Sunnah.”

Source: Siyar Aʾlām an-Nubalāʿ Vol.13 Pg. 268

Translated by Zubayr bin Muḥammad ʾAbbasī