A very interesting bird and helpful to see additional photos.
It's clearly a first-winter bird and one with lots of retained juvenile body feathers. It's clearly not a Red-tailed or Isabelline Shrike as the mantle is not grey enough, the plumage not pale enough, there is insufficient contrast between the tail and the mantle and the primaries are blackish (seemingly never so in juv/first-winter plumage).
So that leaves either Red-backed or Brown Shrikes.
Features that favour Brown are the blackish mask (seemingly never shown in juv/1st W Red-backed), short primary project, lack of white on the outer tail feathers, buffish wash to the breast and flanks.
Features which favour Red-backed are the rather reddish plumage tones (although these could be overstated in the photos), the extent of the retained juvenile plumage and the small bill.
It's difficult to be sure of the pattern on the outer tail feathers, and none of the photos show the tail structure, which is also helpful
On balance, I think this is probably a Brown Shrike, but accept it's not exactly a typical individual.
