No Safari Translate feature in Big Sur
I can successfully access the new Translate feature in Safari after I upgraded my 2020 MacBook Air (Intel) to Big Sur. However, on my Late-2015 iMac I have no such feature. It doesn't appear whatsoever.
For example, when I visit lemonde.fr on my MacBook Air, I see the translation icon in the address bar and the translation itself is very good.
When I visit the same website on my iMac, no translation icon appears. I struggle to see what the difference is on the two devices that would lead to different behaviours across my Macs.
I even use the same ad-blocker and other plugins on both devices.
Any ideas why one would support translate and the other cannot? Does it need enabling?
iMac Line (2012 and Later)