Patches of different colour brick at attic level - what sort of repair is this?

[DIYRalph]

This is probably a really silly question so apologies in advance....just noticed a house I'm in the processes of buying has patchy different coloured bricks at the side of the roof along the chimney cavity:

https://ibb.co/1f8164n

Is this indicitive of damp problems or anything? There was a little bit of damp found on the wall in the attic around the flue.
Or perhaps I'm worrying over nothing!

 

[blup]

Sometimes different coloured mortar changes the appearance of the bricks, or it could be the shadow line of the adjacent roof