DWC issue with buds elongating late in flower(7th Week) any know why this happening?

Sure thats not just genetics? What strain / strains you got there? Just a thought, but are you sure your dark is really dark and your lights are kicking on and off %100 of the time? If they start to go back into veg they'll grow weird. Like I said though, might just be genetics. If they look weird trimmed, cut the ends off and order some different seeds for next time.

the strain is purple wreck... and the lights are on manual timer ......i just checked and all the pegs are down where they supposed to be i hope this dosent mean they re-vegged

its called foxtailing. genetics.

Is this a strain that u have grown before without the elongation or "foxtailing"?

Like said some strains just naturally foxtail like that nothing to worry about.

However I have seen foxtailing on strains due to high N feed during flower or just overfeeding in general.

I have also seen nuggz stretch due to reach from the lamp cause it was too far away the usually grow or plump back into it if the lamp is lowered.
I have also shocked plants out with light leaks which forced them back into veg or what id consider a stasis period before they started flowering again and seen that exact same thing happen.

Could be many things or nothing it could just be genetix.
Hope that helps.