The obfuscation is to fool DPI and firewalls, from reddit's perspective it's the same thing - a mullvad server contacting their server.

I don't know if those are used for the end destination more for skipping firewalls and the sort

QUIC obfuscation relies on QUIC/HTTP-3 traffic being allowed on the network. Some networks and ISPs (especially in highly restrictive countries) also block or throttle QUIC/HTTP-3, meaning the obfuscation won’t help.