If something looks, walks, barks and smells like a dog, chances are, it’s a dog.
The world is complicated enough as is, no need to make it more complicated.
It moved to symfony starting with contao 4. You can now either use it as a self-managed CMS or add it to an existing symfony application to add CMS functionality. Great stuff.
Most of the community is German speaking though, keep that in mind.
Unfortunately, at least in Germany it’s legal. There was a special ruling recently.
(Link in German)
https://www.datenschutzkonferenz-online.de/media/pm/DSK_Beschluss_Bewertung_von_Pur-Abo-Modellen_auf_Websites.pdf