在 ios15.1 ipad 设备无法登录，显示空白界面

While I can't say if it's related or not, currently only iOS 15.8.x is actively supported and monitored/verified for working funnels, early versions that have long gone out of support are not necessarily guaranteed. Does signing into accounts.firefox.com and managing your details there work in general on the device, either in Firefox or Safari, simply browsing to the site outside of the embedded webviews?