When running 20.04 beta in live mode, after choosing language "Português do Brasil" and choosing to try live cd without installation, the correct kayboard layout (Brazil ABNT) is not set in the gnome desktop.
The screenshot attached (Captura de tela de 2020-04-07 05-14-23.png) shows the top-right keyboard set is "pt1", where the correct would be "pt2" (Português Brasil). You have to change manually in order to have your keyboard working as intended when you chose "Português do Brasil" in the first screen.
When you do the proper installation, in the second screen, the correct keyboard layout is chosen (Captura de tela de 2020-04-07 05-22-45.png).
ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: ubiquity 20.04.9
ProcVersionSignature: Ubuntu 5.4.0-21.25-generic 5.4.27
Uname: Linux 5.4.0-21-generic x86_64
NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair
ApportVersion: 2.20.11-0ubuntu22
Architecture: amd64
CasperVersion: 1.442
CurrentDesktop: ubuntu:GNOME
Date: Tue Apr 7 05:08:46 2020
InstallCmdLine: file=/cdrom/preseed/ubuntu.seed initrd=/casper/initrd quiet splash --- maybe-ubiquity
LiveMediaBuild: Ubuntu 20.04 LTS "Focal Fossa" - Beta amd64 (20200402)
ProcEnviron:
TERM=xterm-256color
PATH=(custom, no user)
XDG_RUNTIME_DIR=<set>
LANG=pt_BR.UTF-8
SHELL=/bin/bash
SourcePackage: ubiquity
UpgradeStatus: No upgrade log present (probably fresh install)
Per the bug OP, the bug occurs when the LiveCD is booted and the language is chosen in GNOME.