Hi, author of the formatting package {styler} here. As I judge from a search in your source code, there is no functionality that uses {styler}, in other words {styler} is not a runtime or testtime dependency. You may recommend people to format their code when they contribute, so {styler} is a development dependency. Adding {styler} as a dependency (via Imports: or Suggests:) to your package has the following drawbacks:

• Your user's may install a package they don't need (assuming most people who install your package are useres, not developers). This costs additional bandwith, installation time, disk space etc... If they need it, they can just manually install it.
• I as a maintainer of {styler} have to run reverse dependency checks (R CMD Check your package with my new version of {styler}) upon submitting to CRAN e.g. with {revdepcheck}. {styler} has more than 40 reverse dependencies, which makes this a long process.

For that reason, I suggest you to drop that dependency from your package. If you want to ensure your code remains styled, I recommend {precommit} to apply {styler} on each commit or other tools described in the third-party integrations website of {styler}. Alternatively, there is a new formatter by Posit called Air, currently in beta and much faster than {styler} and able to break long lines, but without R API, not as many third-party integrations and less configurability.

For the removal to take effect, a CRAN submission of your package is required (but the issue is not urgent). For tracking, this issue is referenced in r-lib/styler#1121.