All my old games use web storage and only run on r251.2
Web Storage was replaced by Local Storage about 7 years ago. It happened in Construct 2, before Construct 3 was even out. If you keep using retired features for years and years, you will inevitably run in to problems. This is why you should make an active effort to move away from deprecated features.
Having said that, we haven't touched the Web Storage plugin ourselves for years, so I doubt anything changed on our side. I wouldn't be surprised if some browser change broke it - perhaps browsers are finally removing it, as it was replaced by better storage solutions years ago.
You're probably best off just using the Cordova CLI and doing your own builds locally with a custom configuration. The build service is configured to work with the latest release, and if that ends up breaking old releases, we probably can't do much about it.