CBD flowers and resins are natural products that come from hemp. In most countries hemp and its derivatives contain 0.2% THC or slightly under this amount.
Therefore, hemp resins and flowers contain THC, albeit in very low amounts. Although the percentage of this cannabinoid is very low and it doesn’t cause psychotropic effects, it could be detected in a drug test, leading to a positive result.
Excessive consumption of CBD, either flowers and/or resins, increases the chances of this happening.