Landmark doesn't have a Trump bias. It is the top pollsters that conducts polls in Georgia, and it tends to nail the relative strength of parties in the state. Although their poll have a variety of margins, a combination of their polls will be pretty close to precision.
From polls conducted this month, Landmark has Biden capped at 47%. Aside from one poll earlier this month, Trump is garnering 49% of the vote when you average out the last 4 polls. They're actually very close to 50% than 49%. I think there's a very big problem with the other pollsters utilizing these internet surveys and national populations to model results within swing states. They're essentially oversampling Democrats and underestimating Republicans, as well as the leaners.
BTW... Trafalgar had the race at +6 before election day.
Georgia's not the best state to try and pitch Trafalgar--they were ten points to the right of the 2018 result here.