The bar for scientific discoveries is generally incredibly high and rightly so. In particle physics for example for a discovery to be confirmed it must be independently verified by a second experiment and both the discovering experiment and confirming experiment must be within five standard deviations (or a roughly 1 in 3.5 million) chance of not being a discovery. Its not a perfect comparison because astrobiology is messier but it is useful to see how high the bar is.

For a discovery of the magnitude of life outside our planet the scientific community would probably need something like: a real and well-characterised signal, multiple independent lines of evidence, strong geological context, replication by independent teams, and a serious failure of plausible alternate explanations. Until then, “potential biosignature” is probably the right phrase.

To be clear, I think like you that there probably was life at some point on Mars. I am pretty convinced. But, you and I being pretty convinced does not come close to the threshold of a scientific discovery.