That happened a couple of years ago, around same time as words such as m4 and ak became banned. I even got banned for using M110 when selling springs cos m110 is also a firearm.
The curious thing is that they haven't, not all of them.
I still get 47 hits for "UK" sellers (aye, right) listing "airsoft silencer" and 24 for "airsoft suppressor".
Curiouser and curiouser: when I search for "airsoft suppressor" (but not for "airsoft silencer"), I get shown this item: https://www.ebay.co.uk/itm/223356610666 from some dodgy fly-by-night seller who's probably shipping from a child slave labour sweatshop in China[*].
Listed as "Big Dragon Airsoft Barrel Extension Short 110mm x 34mm (14mm CCW CW Black)". The word "suppressor" appears only in the item specifics as "m4-suppressor", not in the title - and I didn't include the description in the search.
Might not be consistent, but if anyone is wanting to put Killing Words in their listings, the item specifics section could be the place to do it.