Well there are some well-described scenarios of what could've happened to a hypothetical ancient life on Mars. There's some evidence suggestion methane-producing microbes may have lived on Mars 3.7 to 4.1 billion years ago that may have lead to the CO2 and hydrogen being replaced with methane, stripping away the planet's protection and leading to rapid glaciation and total extinction.

Indeed earth has itself had a few close calls with total extinction https://en.wikipedia.org/wiki/Medea_hypothesis

99.5% of life may have died during the Great Oxidation Event. 96% of all marine life may have died during the Permian–Triassic extinction event

TBH it's no short of a miracle that we're still here.

I love that word, “may.” The linchpin of so many suppositions.

Well there we go. TIL.