It’s important to keep the outside walls of your house in good condition. As they deteriorate they become susceptible to damp penetration from wind driven rain as well as “spalling” (the breaking away of the brick face” due to the freeze-thaw effect in colder weather.
This not only damages the walls outside but can spoil the wall plaster and decor internally.
Particularly on older houses the ice and frost can get at brickwork and mortar as the photograph shows.
Avoid problems by asking a good builder to rake out and repoint the weathered mortar and replace the most badly damaged bricks. It’s a skilled job and not one the enthusiastic amateur should undertake!
Smudged mortar on brickwork is not a good look. Unless the joints are properly scored (or “raked” out) the new mortar pointing will fall away before long meaning you have to repeat the process.