Have you checked your brake pads?
Have you checked the level and condition of brake fluid in the reservoir?
Have you been riding with the parking brake on?
Check the lines for kinks?
That is not normal. There is a knob on the brake lever to adjust but that doesn't determine how much you have to pull to engage the brakes, only how far the lever is from the grip to start with.
Looking in my service manual for info. The brakes are mostly hydraulic so no adjustment there but the parking brake is a cable and if that is not adjusted right it could possibly impact the hydraulic operation of the rear brakes.
The manual gives several things to check, same as on any brake system of any bike. Here is the list:
• Air in the hydraulic system
• Low brake fluid level
• Clogged fluid passage
• Contaminated brake disc pad
• Warped/deformed brake disc
• Worn brake disc pad
• Sticking worn master cylinder piston
• Contaminated master cylinder
• Contaminated caliper
• Caliper not sliding properly
• Leaking hydraulic system
• Worn caliper piston seal
• Worn master cylinder piston cups
• Bent brake lever
Some of these are obviously not the issue but still on the list. Some are easy to check but other items would need some level of service work to verify.