A little while ago Conincal annouced that all of it's flavors would no longer support flatpack package by default. But if you have come to like flatpacks you can still use them on Ubuntu and derivites Follow this tutorial to see how.
I will add this I'm not here suggesting that flatpcks or snap is better Just giving info on how to use them The debate about which is better will go on long after this post. in fact most of the time I use appimages for packages I use that are not in the regular repositories.
How to install Flatpak on Ubuntu: Step-by-step guide - OMG! Ubuntu
Learn how to install Flatpak on Ubuntu 18.04 LTS or later to access hundreds of Flatpak apps available on Flathub — it's easier than you think!www.omgubuntu.co.uk
I will add this I'm not here suggesting that flatpcks or snap is better Just giving info on how to use them The debate about which is better will go on long after this post. in fact most of the time I use appimages for packages I use that are not in the regular repositories.