From WCP Discord:

[6:28 PM] Nexim: Has anyone written an addon/WA yet which colors health bars (or similar) according to calculated ttl to help S2M play? As in red above 25 seconds, yellow betweeen 25 and 22 ish, green from 22 to 18, and black-/whiteout at below 18 seconds?

Add something configurable like this,