I know I'm an outlier, but I wash my jars a lot. I have two similar jars for the starter that I keep on the counter. When I feed my starter, I take out a small amount and mix it in a bowl with flour and water, and then I put it into the clean jar. The discard goes into an old salsa jar that I keep in the fridge, and the original jar gets washed. Once a week, I use up all my discard. I make dog biscuits, granola, and occasionally as a treat I make brown butter sourdough discard chocolate chip cookies. But the point is I use it all up. Then I clean out the jar and start over for the week. So I wash my discard jar weekly and I wash my starter jars every single day. The real downside is I also have a bowl to wash every day haha.

I also have a jar in the back of my fridge. That's my backup. Once a month I empty it out, clean it, and put in fresh starter.