I'm processing a 1080i25 TV show, which is actually entirely progressive except for the ending credits. I used TDeint(full=false) on the first two episodes and they ended up looking just fine.
However, on the third episode TDeint produced some weird artifacts. I tried to Yadif the credits just to see what would happen and similar artifacts showed up. However, when I play the original clip on VLC with Yadif turned on, no artifacts are present.
I'm using AviSynth+ r1576.
VLC Yadif output:
AviSynth Yadif output:
TDeint output: