Correctly mentioned the DR200 200Djebel front brake is a bit of a joke and not a very good one

It needs a hefty squeeze to work and I think stuff like locking your front on good dry tar is virtually impossible even after getting a bit of temperature into the disc & pads.
Looking at the brakes working even less I'd have a look at the caliper floater pins. If they are lekker check if the brake releases without binding. If not either the caliper dust seal is ruined or gunked up with filth or the fluid seal is old & hard.
If the brakes were binding you will have to get new pads since they will be glazed over. If they are fairly new sanding the pad surface a bit might do the trick too.
The brake lever should not require anything beyond a drop of oil for the pivot and onto the pusher cam/ bolt after every wash.
Fixing the brakes is a relatively easy and quick operation but should ideally be done by a pro.