I have recompiled the new version, it simply limits itself to restore a flag that is then reported in the configuration file konsolerc. So, to restore the button, is sufficient this workaround :
F="/home/USER/.config/konsolerc"
grep -q "NewTabButton=" "$F"||gawk -i inplace
'{print}/^\[TabBar\]/{print "NewTabButton=true"}' "$F"
