The claim advances recurring pro-Kremlin narratives painting the White Helmets as a Western-backed terrorist proxy and, implicitly, denying the responsibility of the Assad regime for chemical attacks perpetrated during the Syrian civil war.
The "repeated accusations" linking the White Helmets to chemical attacks feature heavily in pro-Kremlin coverage of the Syrian conflict and are never accompanied by evidence. The organization has been credited with saving thousands of lives and documenting the use of chemical weapons in Syria, later confirmed by the OPCW. Due to this, the White Helmets have been the subject of a sustained smear campaign aimed at delegitimizing its activities.
For more information about the importance of the White Helmets in pro-Kremlin disinformation regarding the Syrian war, see here, here, and here.