For 2022, JEE Mains will be conducted in online mode only. JEE Main conducting body - NTA has scrapped the offline mode completely. Only the drawing test for B.Arch will be taken in offline mode.
As for the difficulty level of the examination, it varies each year. Some of the pros of JEE Mains being online are no risk of incorrectly marking answers, no time wasted in filling the OMR sheets, etc.
One of my friends took the online exam of JEE Main and she was quite satisfied with it.
Here are some things you should know about online exams:
All these factors are a constraint in the offline exam. JEE Advance is also being conducted online. It is better if you appear for JEE Mains online, as it will familiarize you with the online exam.
Many of her friends opted for the offline exam, but they all lost crucial marks due to wrong OMR filling.