Seen by the RIPE Atlas probes.
The vast majority of the ISPs which do censor return the localhost address (188.8.131.52 is the real one):
% blaeu-resolve -c FR -r 1000 -q A sci-hub.tw  : 12 occurrences [ERROR: NXDOMAIN] : 2 occurrences [184.108.40.206] : 235 occurrences [127.0.0.1] : 112 occurrences Test #20445233 done at 2019-03-31T18:50:16Z
Apparently, Orange implements the censorship, but not (yet?) Free. SFR is the one returning the empty answer.