I think you can get just a single release from the system, all depends on what it’s detecting. Whether you’re feeling the “pop” or not, if the brakes are otherwise working normally (and it doesn’t happen very often), I feel like the only explanation is some sort of intervention from the ABS control module, which means it’s probably normal compensation for some condition. I’ve yet to come across any sensor issues but I think there are several involved here (accelerometers, yaw, wheel speed, steering angle). Or maybe a suspension issue could trigger it. Anyway, no reason not to bring it up with your dealer, just be prepared to be told it’s normal.
Found one of the Gen 5 threads:
Feedback in brake pedal (not warped rotors or ABS)
I have a 2017 Outback with 37,000 miles. Every so often when I brake moderately hard I get an odd feedback through the brake pedal. It’s similar to the feeling when the ABS is activating, but it’s more pronounced and much much slower (Let’s say for the sake of argument that ABS cycles 15x per…
www.subaruoutback.org