Deep-Seated-Deep-Seeded | Commonly Confused Words

Deep seated

/ˌdiːp ˈsiːtɪd/

Referring to something that is firmly established and unlikely to change.

/dɪːp ˈsiːdɪd/

Commonly mistaken variant of 'deep-seated', referring to something firmly established or ingrained

Deep-seated is the correct term meaning something that is firmly established or ingrained.
The word seated relates to being placed or settled deeply in position.
Deep-seeded is a common misspelling, possibly arising because it sounds like planting seeds.
Remember that seeded is related to planting, not the fixing or establishing something.
Think of seated as sitting deep in thought or opinion, not scattering like seeds.