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 mistakenly form the noun by adding the suffix ... Learn more →
The word "sure" is pronounced with an initial "sh" sound ... Learn more →
People often mistakenly drop the "e" in "loathe", confusing it ... Learn more →
The error is a result of the incorrect transcription of ... Learn more →