Macos 26 beta 1 - beta 3: everything works fine
Macos 26 beta 4: spotlight doesn't work
Macos 26 beta 5 (and probably onwards): Dock, spotlight and launchpad doesn't work
This terminal command also has the same effect and doesn't require disabling SIP, however you will lose the new Spotlight.
sudo mkdir -p /Library/Preferences/FeatureFlags/Domain
sudo defaults write /Library/Preferences/FeatureFlags/Domain/SpotlightUI.plist SpotlightPlus -dict Enabled -bool false
after running these reboot
thanks to @asentientbot

Hooks a feature flag to bring back old launchpad
-arm64e-preview-abi=1 or amfi_get_out_of_my_way=1 boot args (which also means disabled SIP and reduced/permissive security)
having the file /Library/TweakInject/libEllekit.dylib
https://github.com/doraorak/Dylinject
inject the dylib to dock
make clean package
clicking launchpad icon again doesn't exit launchpad. FIX: Go into the applications folder and replace Apps.app with the original Launchpad.app
(terminal command doesn't seem to have this issue)