I just came back this week from a return trip CPH - GRU by CDG with AF in J - and then connecting in GRU with LATAM to MVD and back to GRU again with LATAM - all flights booked on an AF ticket.
CPH-CDG: No special greeting and no special attention - and was even asked by the purser before disembarking whether I was going to stay in Paris for many days (I had a short connection of around 1 hour and 20 minutes)....
CDG Terminal 2E L - Due to the short connection I went directly to the gate where I asked for preboarding - which I was promised but then general boarding started and the AF staff at the gate had completely forgot about my promised preboarding....
CDG - GRU: Special greeting by the chief purser and an apology when mentioning the issue with the lacking preboarding.
GRU - CDG: Excellent attention & service and I had a very good & long chat with the chief purser about the Ultimate program and the lack of consistency - I actually even told her about this forum and she said she would check it out.
When arriving in Terminal 2E at CDG on the way back it was a total chaos at the security control with a very long line and I asked 3 different AP-staff whether it would be possible to skip the line or get any preferential treatment (I had a connection of 1 hour) - this was of course refused so I had to run to Terminal 2F after spending close to 30 minutes in the line.

Due to the situaton at the security control in 2E I did unfortunately have time to try to the new Ulti-lounge in terminal 2F at CDG.
CDG-CPH: Good service & special greeting by the purser and I also got a cup of coffee before departure as the only passenger traveling in business class

Btw due to COVID-19 all lounges in Terminal 3 in GRU are closed until 11am - which kind of sucked with AF arriving at 6.30am on the outbound leg and my connecting flight with LATAM departing at 2pm.....

I am going back to MVD again this Sunday evening but have booked with LX because of a better connection with LATAM in GRU - and because it does not really make any sense to accumulate any more UXP this year because I am already at more than 2,700 UXP for this period (my qualification period ends Dec 31st this year) and there is no carry-over of excess UXP.
I have actually also booked a couple of other tickets to South America for the coming months either with LX or LH - mainly due to the lack of carry-over of excess UXP, but also because of the lack of consistency in the additional service level being offered to Ultimates.