UFH mat in bathroom

[SSE]

Was at a job yesterday & whilst running cables for lighting in a side attic space I came across something I’ve not see before (not surprisingly). The couple had a new bathroom installed last year & by the looks of it whoever installed the underfloor heat mat, they never measured the UFH mat correctly for the size of the bathroom. So from what I can see what they’ve done is when they got to the last tiled part of floor they’ve drilled a hole in the floor & stuck the heat mat wire under the floor & run the heat wire free in the void for about 300mm into the attic space & then have fitted a thick length of ply to joists, ran the excess cable out on top of the ply & then fitted another bit of ply on top of this. Doesn’t seem safe to me, should I notify the customer? I’ve been reading heat mat cable in air is a no no.