I see in the documentation that you didn’t change the settings. I also saw in the community that similar errors have already occurred before. Could you check the following apps: fly-foodbank-dev-web, ?
The issue was in secret ENV variable. I have only one idea: when the fly.io team automatically migrated the app to V2 they “left” new env variables and moved only first versions. I got the idea because the app also didn’t have one more value for one ENV variable REDIS_PASSWORD