I'm using Eclipse 20210312-0638
I have unchecked "Download artifact sources" and "Download artifact javadoc" from preferences (First picture). It's still downloading them (2nd picture). Is there any other configuration that I should change?
Someone already filled a bug at Eclipse: https://bugs.eclipse.org/bugs/show_bug.cgi?id=576112
Apparently, it's fixed in M2E, but not yet released. Though, you can update on the latest snapshot as explained here: https://github.com/eclipse-m2e/m2e-core/issues/252#issuecomment-926379620
It solved the issue for me.
Until the release in Eclipse, you must add this update-site: https://download.eclipse.org/technology/m2e/snapshots/1.18.3/latest/
Accoriding to @Nis this is now released in the standard Eclipse update-site, so you don't need to add the preceding update-site anymore