->to_string — real Mojo::DOM re-serializes the (possibly-modified) tree back to markup; this shim is read-only (no ->remove/mutation support), so the original source markup never actually changes after parsing, and returning that original string verbatim is equivalent to a real serialization for every real call site in the legacy plugin corpus (both existing uses — EHentai.pm/Pixiv.pm — only ever call it on the root Mojo::DOM->new(...)/->dom result to substring-search the whole page, never on a sub-node after ->at()/->find()).