This was fixed 6 months ago in the packaging Git repository (see https://salsa.debian.org/debian/doas/-/commit/4686a00819d963b88b5982fe57cf6cf717765997), but the maintainer never pushed the update to the Debian archive (maybe Scupake thought that he already did that?).
You could try building the package from the repository if you really want to use the persist feature.
