In brief
In multi-line flex layout, align-content distributes cross-axis space between and around lines. It does not replace align-items for individual items.
Useful to know
In multi-line flex layout, align-content distributes cross-axis space between and around lines. It does not replace align-items for individual items. [1]
If every card occupies one flex line, changing it may not produce the intended effect. Check wrapping, available cross-axis space and line count before adjusting line distribution.
Sources
For further detail and to check the information: