There are limits to how quickly you want to charge batteries, but historically, chargers provided with consumer electronics don’t get all that close to those limits.
1C was a good rule of thumb, and many LiPo batteries still recommend keeping charge rates at or below that, but it does depend on how the battery itself is spec’d, as 1C isn’t a hard rule with Lithium batteries. Without Apple giving us details, we don’t know the limits of the battery Apple uses.
However, while a 140W charger can technically exceed 1C on the 16” MBP, Apple’s statement is “50% in 30 minutes” for fast charge. This corresponds with a charge rate of 1C. What this means is that Apple’s using the charger to let you charge as close to 1C as possible, while also having a little headroom in the charger for the laptop itself. I wouldn’t be worried.
