(PC) Severe Packet Loss After Season 3 Update

After 3 days of troubleshooting, I isolated this down to DSCP tagging.  Which for the non network engineer readers, is mechanism for internet traffic to be marked with a priority so it can be treated differently on networks.  Xbox has an option (Settings > Network Settings > Advanced Settings > QoS tagging) that I'd had turned on.  Turning off the issue/rebooting, resolved the issue for me immediately - I verified this by turning it off and back on across four different 80+ player BF2042 servers and it was consistently the culprit.

So for Xbox players, thats the work around.  But there will likely be another work around / trigger, that might help you PC players suffering the issue - and if my theories right, it would explain why some of BF2042 is complaining but not all; using gaming routers.  If you run a gaming router like Asus, or Netgear Nighthawk - that performs network prioritisation/QoS functions, its worth trying to turn those features off temporarily for your gaming PC/console, to see if that works for you around.

The root cause, I suspect, is that EA/Dice servers (or netcode) is using these DSCP tags in some way - since one of the Season 3 updates.  Seemingly poorly.  If I had to guess, it would be something like their prioritisation queues on their AWS servers for the priority traffic is either optimised for the 64 player server count and not dealing with higher traffic load - or its not been setup properly to cascade/overflow. 
In laymens terms, its like turning up to a nightclub with a VIP card on a busy night and the bouncer letting you in last after all the other peasants - it should have the opposite effect.
As per my above report, I've been playing BF2042 since launch, same Xbox/network environment with this DSCP tagging setting turned on - and it only became an issue in the last ~3-6 weeks.

Hopefully the findings are useful to others, but more hopeful that EA community managers flag with some Dice folk