Bug in prefix filter

[hannahbast]

The following query on https://qlever.cs.uni-freiburg.de/Wikidata returns a name starting with "ext" as the first result, despite the prefix filter for "exp". When running the query with "expo" instead of "exp", the result list is empty, despite many entities with a name starting with "expo":

PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
SELECT ?entity ?name WHERE {
  ?entity @en@rdfs:label ?name .
  FILTER REGEX(?name, "^\"exp")
}