Yep, Really simple .
Your calipers/pads are hanging up. Which means the side that wears fastest is not retracting completely so the pad stays engaged longer and drags the pad on the rotor regardless of pedal pressure. Question does it pull to the opposite side when braking? Does the problem get worse as the brakes heat up in repeated hi speed stops. Does the vehicle pull one way on flat roads but the opposite under braking? Only one side is working, the opposite is a locked piston ,frozen in the bore.
Solution: rebuild the calipers and replace the pistons if scared. At the minimum the calipers and retaining pins should be checked, cleaned or replaced. File flat the resting points on the carriers, use appropriate caliper hi-temp grease on the caliper/carrier/pad contact points. Make sure the hoses are not collapsed and bleed the system.
. ..do not just replace the pads and hope for the best as the issue will only get worse up to and including the caliper locking up under full panic stop. Most of our vehicles need the seals in the caliper replaced at the 100k mark especially if your vehicle has not had proper brake fluid changes or has been subjected to years of use. After 10 years it's time. .......

Need a method of confirmation on the pads hanging up? Drive 30 mins with a few quick stops and measure the rotor temps side to side. The hotter one will be your issue side.

__________________

2005 X5 4.8IS
The Blue ones are always FASTER....

Current Garage:
2005 X5 4.8is
2002 M5 TiSilver
2003 525iT
1998 528i
Former Garage Stable Highlights
2004 325XiT Sport
1973 De Tomaso Pantera, L Model
1970 Dodge Challenger T/A 4 sp Alpine White
1970 Dodge Challenger T/A 4 sp GoManGo Green
1971 Dart Sport, “Dart Light” package
1969 Road Runner 383
1968 Ply Barracuda 340S FB Sea-foam Green