By identifying residues from labeled jars found in an ancient Egyptian mummification workshop, the researchers were able to show the process involved complex chemistry and exotic ingredients, including resins sourced from a continent away. https://www.science.org/content/article/secrets-mummy-making-revealed-residues-ancient-urns
@estherschindler
Considering that plus the labor involved in embalming it makes sense the only some people were embalmed.