expression, noun
malicious advertising; deceptive ads
Refers to online or offline advertisements that are harmful, misleading, or fraudulent, such as phishing ads, fake news promotions, or malware-distributing banners.
このサイトには悪質な広告が多く表示される。
Many malicious ads are displayed on this site.
悪質な広告をクリックしないように注意してください。
Please be careful not to click on malicious advertisements.
Compound of 悪質 (malicious, of bad quality) + な (attributive form of copula) + 広告 (advertisement). The phrase is a straightforward modern coinage reflecting concerns about harmful online advertising.