genMtprotoLink appended the panel remark as a URL fragment (tg://proxy?...&secret=...#remark). Because secret/server is the last query value, lenient Telegram parsers fold the "#remark" into it and the imported proxy breaks with "incorrect client random". Telegram proxy deep links have no name field, so emit a clean link on both the backend (internal/sub) and frontend (inbound-link.ts). The remark still shows as a separate tag in the inbound info modal, which reads it from genAllLinks, not the URL.
Guards: Go TestGenMtprotoLinkFields asserts no fragment; the frontend mtproto link test asserts no '#'.