I worked for Eurotunnel/Getlink, actual operator of the tunnel(s), as a software architect between 2012 and 2020.

I can tell several fossils were displayed in the main office building both in France and in UK.

I remember a big ammonite, like 90 cm wide at least, displayed on the French Terminal, main office building with a sign next to it explaining the context of the discovery.

The article is about previous attempts to dig a tunnel, in the 19th century etc.

Crossrail (now the Elizabeth Line) had an exhibition in London at some point.

The artifacts they'd dug up were from the stations and underground crossings, i.e. the traditionally-dug bits.

The tunnel boring machine just crushes everything. (And for that line is mostly deeper than artifacts anyway.)

https://www.samphirehoe.com/about-samphire-hoe/creation/ - on the UK side, most of it ended up being used for land reclamation.