There are way too many hybrids out there that can produce pitchers similar to this to give any specific answers without being able to see diagnostic traits such as leaf shape and attachment to the stem, other pitchers to determine if this is normal appearance or even fully mature appearance, etc and even that might not narrow it down. Anything involving maxima, veitchii, even spathulata and its relatives could be among possibilities for this cross though I would not lean toward tiveyi as just about every plant I have seen of that hybrid has far tubbier pitchers and much less of a pronounced hip (neither parent species shows much of a hip even in young pitchers, and the hybrid should not either). Something with spathulata, even perhaps spathulata x veitchii like the similar N. 'Judith Finn' would be more to my guessing.
Also, N. x tiveyi is not a grex, but a Latin hybrid name for anything that is maxima x veitchii or the reverse cross (a grex would be a single cross only between two particular clones of these species, unidirectional).