It’s over for courgettes put up in jars over a simple boiling water bath: what survives in there doesn’t need air, and it doesn’t change the smell
Decades of family canning recipes for courgettes are scientifically unsafe, and the danger is invisible. The USDA pulled its own zucchini canning instructions because boiling water simply cannot reach the temperature needed to kill botulism spores, yet the sealed jar creates a perfect breeding ground for the deadliest toxin on earth.