→ you’re right, just put a 720x576/Pal/50 (interlaced video to progressive without doing de-interlacing) video to 1080p/25, and the artifcats are not there !
speed is 0.36spf but as it’s SD, the speed up is expected, i must try with the 3.1.6 to see if it’s the same speed or if it’s a bit better.
model used this time which does not make artifact :
prob-v3-fgnet-fp32-576x384-2x-ox.tz
tested with 95% ram use, and power save mode disabled. will test with it turned on.
→ Power Mode turned on bring Artificats back !!! (ahah). : speed : 0.32spf
Switch off again the powermode on the same SD video bring back the 720p/1080p artficats 
lol
i put back the powermode switch one and artifact is back in this mode as well.
→ New Video, 720x576/25 mpeg interlacted → 4K / 25
Powermode turned on : speed 0.79spf Artifact are there
powermode turned off : artificats still present but different. 1.05 spf
