Thinking about it, over the years I've been fired surprisingly few times. Most bands had run their course and folded or I was the one that quit. In all that time I can only think of 2 bands I was sad to leave. That's not bad for over 45 years.
The guitarist in the acoustic duo changed from playing blues and ragtime to authentic English civil war songs and I didn't see much room for a bass of any kind. Was I pushed or did I jump? A bit of both really.
One band leader thought I didn't have the commitment because he got a gig on the day I asked him not to, months before, and I didn't chose the band. The rest of the band was fired for various silly reasons over the next few months. It was a good band, but that guy really was an a****hole.
One band had a drummer who, while having a good reputation was a nightmare to work with, decided he wanted to work with different musicians. He quit and his price for coming back was that I was fired. The singer obliged. They are still going and after a few more personnel changes don't sound very good. In this case I like gloating.
Nothing much has changed in 45 years. Bands are still a mix of selfish idiots, a***holes, dreamers, talented players and normal people.