These are genuine graves with genuine dead people inside and genuine crosses above them, often trying to describe the contents, such as "17 Ukrainian soldiers".
edit: source = https://apnews.com/article/russia-ukraine-europe-2c77447fda4...
Bucha though, I've seen drone footage of civilians getting executed by Russian BMPs.
You could argue the systematicity of that process, but Russia's occupation west of Kyiv undeniably caused a large number of civilian casualties