Please post a phot for any suggestions...

White brick generally is not painted white. It is fired in the kiln as white. If yours was physically painted, then it is a huge job to redo so that it sticks. Find a pro familiar with Loxon.

All paint colors change over time (fade from sun, yellow if oil based, etc). It’s a shame that the previous painter was short sided and left areas unpainted. IMO your options are to match the existing color (even if it’s different from what’s in the can) or repaint everything. Repainting everything will be best option, but a lot more expensive. You could get a quart of paint that matched and try touching up and see how good/bad that works before biting the bullet for a full repaint. If you chip off a piece of paint about the size of a quarter and take to the paint store they can match it pretty closely. If the bare spots are just on one side of the house you could probably get away with just repainting that side.

yes, thanks for this, sounds like the best option.....