I'd say it's more like they're getting search data from Google.
eg: I search on some medical condition (which I might or might not have) and the next thing I know, all Taboola 'chumbox' blocks are littered with 'ads' (which aren't ads that 'sell' anything) about said condition. Just extremely low quality links with zero value.
It would be pretty shocking if Google were sharing search data with anyone, let alone Taboola.
Others in this thread mentioned that Taboola used to have literal malware that would replace Google with a google-lookalike. Maybe you have that malware?
eg: I search on some medical condition (which I might or might not have) and the next thing I know, all Taboola 'chumbox' blocks are littered with 'ads' (which aren't ads that 'sell' anything) about said condition. Just extremely low quality links with zero value.