The included LibreOffice is a Major version which will never change as long as you don’t change your system version.
To solve this, remove it from Ubuntu Software or sudo apt purge libreoffice*

Then install the snap version in Ubuntu Software (You will see another LibreOffice entry. In description there is source : snap store)
or
snap install -y libreoffice

You can also use the PPA :

sudo add-apt-repository -y ppa:libreoffice/ppa && sudo apt install -y libreoffice