I had the same problem. We fixed the issue by specifying the Expires or Max-Age of the cookie. iOS has the problem of losing cookies without Expires or Max-Age that exist in web views in the background during memory cleanup. I was able to find out from the cookie test on iOS safari. I haven't tested it in all versions of iOS, but it happens in iOS 15 and later.
Topic:
Safari & Web
SubTopic:
General
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