Interesting. May be I can add a gradient from red -> yellow -> green with effected minute count, normalized to gradient threshold percentage. Let me try doing that
I think it's worth deciding what you want to communicate. If it's "we have good uptime, but we may lie", then it's a green bar always. If it's "we're honest about our downtime" then the colors should be distinct so users can notice and inspect the days that are <100%. A gradient runs the risk of looking "all green" even when some downtime minimal happened. If that's not the goal, then I'd recommend a step function (green, yellow, red, for example).