This guide will show you how to change Slingshot back to how it should looks like.
First we need to get older libs. One for Slingshot and one for elementary Tweaks. Open the terminal and copy/paste:
cd && cd Downloads wget https://github.com/ATVG-Studios/applications-menu/releases/download/2.5.0-c2/libslingshot.so
Next thing is to backup the current libs, so you can switch back if needed. Copy/paste:
sudo cp -r /usr/lib/x86_64-linux-gnu/wingpanel/libslingshot.so libslingshot.so_backup
Now you can copy the downloaded libs into Slingshot and elementary-tweaks:
sudo cp -r libslingshot.so /usr/lib/x86_64-linux-gnu/wingpanel
Lastly you need to download the schemas that tells on how Slingshot shall be structured: Download here
And you need to copy into /usr/share/glib-2.0/schemas
sudo cp -r io.elementary.desktop.wingpanel.applications-menu.gschema.xml /usr/share/glib-2.0/schemas sudo glib-compile-schemas /usr/share/glib-2.0/schemas killall wingpanel
Now you have the old look and feel from Slingshot.
To prevent newer release of slingshot and elementary-tweaks to reset the tweaks you made, you have to hold to packages back. Copy/paste:
sudo apt-mark hold slingshot-launcher
Tested on: elementary OS 5.1.4 – 5.1.6