After installing Rider 2020.1, such hints as shown in the screenshot appeared. There are many +1
in grey showing up after different lines of code.
How do I disable them?
I was able to reproduce your "+1". It seems to be the plugin CognitiveComplexity giving you that number. It's a counter which helps you on determining the complexity of the code you're writing. Pretty cool plugin I didn't know it. Disabling it will make the numbers disappear. I don't think you can let it enabled and avoid seeing numbers: it's the way it works to show you complexity cost.
To disable or enable plugins, go to Settings > Plugins, and then deselect CognitiveComplexity.