No, Home Assistant was not removed and on my RPi 4 it’s shown as installable.
Can you please fill out the troubleshoot template, maybe your device does not match the criteria to install it.
It’s also interesting that I can not see “domoticz” in my list
edit:
So I guess you are not on Debian Bookworm, bc on Bookworm you could install Home Assistant, but not Domoticz (bc of some trouble with libssl version)
btw you could check for available software and why it might be missing as follow
dietpi-software list | grep -E '157|140'
should give following on Bookworm
ID 140 | =0 | Domoticz: Open source home automation platform | DISABLED for Debian bookworm | https://dietpi.com/docs/software/home_automation/#domoticz
ID 157 | =0 | Home Assistant: Open source home automation platform | | https://dietpi.com/docs/software/home_automation/#home-assistant