install/60222: on the usb installer, the installer seems to hang right after booting, having an underscore looking character frozen in the top left corner

["mcq%disroot.org@localhost via gnats" <gnats-admin%NetBSD.org@localhost>]

>Number:         60222
>Category:       install
>Synopsis:       on the usb installer, the installer seems to hang right after booting, having an underscore looking character frozen in the top left corner
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    install-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri May 01 14:50:01 +0000 2026
>Originator:     Benjamin Lee McQueen
>Release:        NetBSD-10.1-amd64-install.img
>Organization:
none
>Environment:
unsure
>Description:
when booting the installer, a black screen and an underscore frozen in the top left corner results.  it takes no input, i can't type or do anything inside of it.

i am using:
MSI PRO B650-vc WiFi motherboard
RX 580 (main GPU)
RTX 4060 (also tried)
16GB of DDR5 RAM
AMD Ryzen 5 8400F Processor

using an HDMI cable
UEFI system, by the way.
UEFI in the BIOS as well, not on CSM.
>How-To-Repeat:
unsure, but reference the hardware
>Fix:
not known