After installing Big Sur, I was having issues with Spotlight.
Applications were not listed and generally it didn't seem to work properly.
These are the steps that helped me to fix Spotlight indexing on Big Sur.
Saw the following error when I was trying to install an npm dependency, that had native C bindings:
My disk space was running low. I had less than 100MB of free space. I was sick of running low on disk space.
Clean My Mac wasn't an option. I don't want to spend 40$ for a cleaning tool, if you're so inclined feel free to do it.