While using TSUp for TanStack Form, I ran into an issue where this in a class context was being replaced with this$1 incorrectly.

As it turns out, this is a bug in rollup-plugin-dts: Swatinem/rollup-plugin-dts#279

This in itself isn't a good reason to replace the package, however it seems that while I was investigating I saw that the package is in maintainance mode: Swatinem/rollup-plugin-dts#277

Which might be a good enough reason to migrate off of the tool.