Go to https://rest.wikimedia.org/fr.wikipedia.org/v1/page/html/Anne_Delb%C3%A9e , search for " :" (space colon) and inspect. Observe that the space is wrapped in a span and converted to an nbsp: <span id="mwXX" typeof="mw:Placeholder"> </span> (you probably won't see in the DOM inspector, but $0.textContent.charCodeAt(0) returns 160 instead of 32). These spans get alienated in VE, because they don't have a useful type, which makes for a very strange editing experience. This also breaks our whitespace detection for link text, see T92896.
mw:Placeholder is very unhelpful. Ideally I would prefer that these spaces just be plain text, but for round-trip reasons I understand that's unlikely to work and using an mw:Entity wrapper is probably more realistic. With an mw:Entity wrapper we'd still have to work around this issue in the link text whitespace code in VE, but at least these spaces wouldn't be alienated any more.