There seems to be a fabric mod to fix it: https://modrinth.com/mod/centered-crosshair
Would be good if it’s fixed upstream in vanilla.
At least it shows, it does not show on JE.
Annoys me as well, this was not an issue on old (ancient) versions like 1.8 as far as I remember?
This is not fixed despite saying so here and in the launcher changelog, the dependencies still has (only) the two dash version, libgdk-pixbuf2.0-0 (>= 2.22.0) on the launcher version 2.1.3 obtained from minecraft.net, checked just now. Trying to install with the replacement package installed manually, which has 3 dashes, libgdk-pixbuf-2.0-0 fails since it strictly wants the two dash version (which was a transitional package that got removed from debian and ubuntu in latest releases)