Until this year, the GMC Canyon has offered six trims in two drivetrains: SL, a base model simply called Canyon, SLE, All Terrain, SLT, and Denali, with all but the SL available in either 2WD or 4WD. GM Authority credits "dealer sources" for news that the 2021 Canyon has had its trim steps overhauled. According to the chart in the report, the SL and SLT are no more, the base Canyon gets replaced by a trim called Elevation Standard, and SLE turns into Elevation. We already know that All Terrain has given way to AT4, while Denali remains in the top spot. Trim content doesn't change with the names, but there's no equivalent for the SLT trim in terms of spec.
The GMC site lists the 2020 SLE and SLT on the same page, and a shopper must burrow into the spec comparison page to figure out the differences. The SLT only comes with the 3.6-liter V6 and eight-speed transmission, and makes features like remote start, climate control, heated mirrors, heated seats, hitch guidance, and a spare tire standard equipment. It also chromes the exterior door handles, and offers a Cocoa/Dune leather interior that can't be had on the SLE. It's possible the SLT's $4,700 premium over the SLE led more buyers to start with the SLE and add the engine and options they wanted.