Presumably, it is based on claims by Russian and Syrian authorities. These are not impartial sources, and they delayed access of international inspectors to the site.
OPCW has confirmed use of chemical weapons by Syrian government during the civil war at several separate occasions.
https://www.independent.co.uk/voices/syria-chemical-attack-g...
This might by one of those rare instances https://www.informationliberation.com/?id=58259
However, outside MSM, there are questions across the political spectrum however. Such as...
https://www.alternet.org/grayzone-project/what-really-happen...
https://www.foreignpolicyjournal.com/2018/04/12/idiocy-is-br...
However, Iraq WMD's were all reported by legitimate news sources at the time. Sometimes in the present, it is never clear as to what may or not be ultimately revealed.
Leave all that aside. The way to contradict an on-the-ground report the bias of which is obvious and unacceptable to you, is to show us an on-the-ground report that contradicts it, the bias of which is more acceptable to you. This has the benefit of being less insulting than shallow assumptions about my media habits, oh and also it has the benefit of making any logical sense whatsoever, in contrast to the three sentences of meaningless pablum we see here.
Tick-tock.