In Jain Dharma, watching 18+ content is considered harmful to the soul because it increases kashāya like kāma, rāga, and attachment, and it weakens brahmacharya and self-control.

For a layperson, it is not treated as a monk-level fault, but it is still not ordinary or trivial. The needed purification should be sincere and serious, according to the person’s intention, habit, and degree of involvement.

A proper Jain response would be:

• Sincere pratikraman
• Heartfelt repentance
• Firm resolve not to repeat it
• Sensory restraint
• Avoidance of such content and situations
• If it became a repeated habit, then deeper atonement and stricter self-discipline are needed

So, for a layperson, it is best understood as a serious impurity of conduct, but not at the same level as a monk’s violation. The purification should be real and earnest, not casual.

In short: ordinary? No. Monk-level? Also no. Serious layperson-level repentance and purification? Yes.