Proxy DNS when using SOCKS 5 not working properly in Firefox

[5uy4n9]

enable Proxy DNS when using SOCKS 5 and proxy with added socks5 server by SmartProxy, Firefox still send DNS request from local, when disabled SmartProxy, use socks5 proxy in Firefox Network Settings don't have this problem, the same problem also happens in SwitchyOmega (Steps to reproduce in FelisCatus/SwitchyOmega#2304 ), seems like a webextension problem?

someone else also has this problem: https://www.reddit.com/r/firefox/comments/ryhzsl/possible_dns_and_ip_leaks_with_socks_proxies_in/ https://stackoverflow.com/questions/45795097/webextension-proxy-api-resolve-dns-entries-on-socks5-proxy-not-on-the-local-sy