Clients with Client Reset Packet Mod installed still can't do instant server switch.
After doing research on this, it is clear that the plugin overwrites the player's mod list with registered channel list, but Client Reset Packet mod does not register any plugin channel so it got hidden, making the plugin unable to detect CRP.
I've made a PR to fix this but not so perfect because Velocity does not provide PlayerChannelUnregisterEvent, uh, painful. Maybe we need to talk with Velocity devs about this. I think it would be better to let Velocity maintain the channel list. We don't need that anymore because newer Velocity did that.
See PR #71