Over recent years I have noticed that many mooring service companies, ours included, have started using wire ties instead of seizing wire to secure shackles.
I always ask for seizing wire and even provide the wire when the mooring is commissioned in the spring.
But even so, while checking today, I found wire ties.
Fixed now. Note the locking turns so that even if one strand breaks the seizing will stay put.
Worth checking what your mooring service company does.