Log Vs Meters in WoW Classic

This has been my first delve into WoW and combat logs in general, so I apologize if this question is glaringly obvious.

In light of BGs dropping and a patch release in Classic, a lot of people I know were bunch of errors and inaccuracies in quite a few different addons (threat calculators, healing UIs, etc). While these have for the most part been fixed, i found a major discrepancy between my addon numbers and the log numbers. Are the combat logs affected by patch releases in the same way?

No, Blizzard’s combat log data is fine.