Yes, you'll notice some resistance when bending your knees deeply — think tucking or recovering from a fall. The pad won't stop you from skiing, but you may need to slightly adapt your technique during deep flexion. For race training and gate running, most skiers find this trade-off acceptable because these pads offer significantly more impact protection than more flexible options.
Moderate restriction pads are designed for skiers who need that higher protection level, like slalom and GS racers hitting gates, or anyone doing intense training where knee impacts are likely. If you're just freeskiing or cruising groomers, this level of restriction probably isn't worth it.
Before buying, try the pads on and move through a full range of motion: deep squat, high tuck position, and lateral movements. If the resistance feels like it's fighting your natural skiing stance, consider stepping down to a slight restriction pad instead.