I am not sure what happened in your case with ES or how that would be possible. It sounds like maybe the app just pushed you an advertisement as a notification. Notifications can be disabled on a per-app basis but I think it is pretty reasonable that they are enabled by default.
[1] https://www.androidpolice.com/2016/05/10/es-file-explorer-up...
[2] To those who might laugh at my paranoia about ES while I happily use Zoom, I teach classes and it is not an easy choice not to use Zoom.
They got worse, also with updates since they were acquired Lenovo. Last time that I surveyed the Android landscape (~2 years ago), Nokia was the place to go for a pristine Android experience with quick updates.
Btw, all these distributions (Lineage and Cynogenmod before that) don't benefit from automated updates. So that is another headache to remember to manually reflash/upgrade.
That varies by the ROM. Many do support automated OTA updates. (https://www.androidexplained.com/lineage-os-ota-update-locat...)
I haven't found a LineageOS device that will pass the SafetyNet checks yet, though.
Is LineageOS still signed with testing keys?
I had ESFileExplorer installed on a Nexus 7 tablet I barely used. One day I start it to find the charging has switched to “smart charging” where this software shows a banner ad on the home/charging screen. There is no end to the madness of what each app can do or even allowed to ask for.