I've just tested it as I use adblock as well. The content is coming from cdn.taboola.com, using the default blocklists, it should be blocked:
:::
::: domain 'cdn.taboola.com' in active blocklist
:::
- no match
:::
::: domain 'taboola.com' in active blocklist
:::
+ taboola.com.cn
+ taboola.com
:::
::: domain 'cdn.taboola.com' in backups and black-/whitelist
:::
+ adb_list.adaway.gz cdn.taboola.com
Confirm adblock is in fact filtering, by running on a client that's using your upstream DNS with adblock:
nslookup cdn.taboola.com
If you get NXDOMAIN that means adblock is filtering and the JS loader shouldn't be able to load. Browsers like to aggressively cache these days. If it does return DNS info, something in your DNS chain is bypassing adblock.
Adblock is definitely working. I tested it by loading the Daily Mail (not a site I usually visit, but I know it is stuffed full of adverts and scripts). The Taboola content is somehow getting through on this page:
I'm seeing these messages in the logs. Do I need to install another package?
Wed Jun 9 15:50:52 2021 user.info adblock-4.1.2[7788]: Please enable the 'DNS Report' option to use the reporting feature
Wed Jun 9 15:50:54 2021 user.info adblock-4.1.2[7880]: Please enable the 'DNS Report' option to use the reporting feature