I’ve noticed that with some third-party themes there is an anomaly when making a comment line with 6 or more ‘#’ symbols (i.e., to make a sort of comment “bar”). Here is a screenshot with the Ayu Dark theme (https://packagecontrol.io/packages/ayu) illustrating the issue with R syntax highlighting. I’ve also noticed the issue with Julia syntax highlighting, although that is a third-party package. I’ve also seen this issue with other third-party themes, e.g., Monokai Pro, Night Owl… but not with built-in themes like Monokai and Mariana.
I’m using Sublime Text 4 Build 4126 on macOS 12.2.1.