https://en.wikipedia.org/wiki/Gro%C3%9Fvenediger has 3666m, https://cs.wikipedia.org/wiki/Grossvenediger has 3662m, but https://de.wikipedia.org/wiki/Gro%C3%9Fvenediger has 3657m, which is the most recent measurement. The summit used to be on ice, formerly on even 3674m, but much of it melted away so that the peak is now really 17m lower. This happened to many peaks in the alps and in other mountain ranges, unfortunately. Other good examples nearby are https://www.openstreetmap.org/node/256042855 (also with mass movements involved) or https://www.openstreetmap.org/node/256042805.