Every honest answer here starts with the consent position, because the technical fixes that ignore it are the ones that produce a fine.
Most of what is sold as conversion tracking work is a technical answer to a problem that is half legal. The gap between what a business sells and what its ad platforms report has two causes, and only one of them can be engineered away. Which half is which decides whether a given piece of work is worth buying.
These articles put a number on the gap rather than a description of it, and they say which part of it is recoverable.