Ah - if only! Sadly it's more complicated. Many will live with it, especially if it's a mild strain, and many, though carrying it, recover and resume a normal life - though it might take a year or so to get there (and a lot of people will have culled such a bird before then so don't even know it). But a bird suffering the double whammy of this and something else might not make it. Mortality is usually low, and most birds recover without anything more than a little TLC. Repeated mild infection seems to confer some immunity from symptoms even if the bird is a carrier. And some are asymptomatic carriers from first exposure.
This is one of the best leaflets I've found to date about it
https://drive.google.com/file/d/1oz-jemqYjmVj0wEUj4gAI5VQ6idPotUU/view
this is good too
https://extension.umaine.edu/livestock/poultry/mycoplasma-gallisepticum-faq/