How tight feet affect your back

Your Superficial Back Lines (SBL, right and left) connect and protect the entire posterior (rear) of your body from the tip of your toes to your forehead.
The SBL does this in two pieces, toes to knees and knees to brow, but when the knees are extended it functions as one continuous line of integrated myofascia.
Its function is to support the body in full upright extension.
The constant demand on the fascia requires it to have extra-heavy sheets of fascia in the Achilles tendon, Hamstrings, thoracic and erector spinae and neck.
When there is an imbalance between the two SBLs, there are common compensations in posture that occur including, as many of us know, hamstring shortness, knee hyperextension and anterior pelvic tilt.
As a simple test, when you bend over to touch your toes, does one hand hang lower than the other?  If so, return to standing and roll a tennis or golf ball on the side with more limited movement, using slow and thorough moves over the whole foot from the toes to the edge of the heel.
Try bending again and see if the hand reaches the floor more easily now.