The developer is addressing these concerns in a number of ways. First, the XP earned by completing a match is going up by 10%, and the daily bonus XP is getting a 40% boost. For weapon XP, BF Studios is reducing the XP needed to unlock any weapon's first 20 attachments. The developer said you can expect that process to be about twice as fast.
The HDR is still the most powerful and most popular pick for Warzone in Season 6. The recommended attachments are mostly the same for a standard build of the gun, but Season 6 does feature night maps for Verdansk and Rebirth Island, making thermal scopes much more viable to use.