It is an eggcorn error.
"Deep-seeded" sounds similar to the correct phrase and may lead people to think of seeds planted deeply, creating a plausible but incorrect mental image.
The correct phrase is "deep-seated."
People often confuse past tense forms with past participle forms, ... Learn more →
People often make this error due to phonetic confusion, as ... Learn more →
People often use "comprised of" mistakenly because it sounds similar ... Learn more →
People might mistakenly assume that "worser" is the comparative form ... Learn more →