The issue seems to come from defaulting same-site to lax. If I setting `network.cookie.sameSite.laxByDefault` to `false` fixes the issue in Nightly and enabling it breaks the site in release.
Bug 1732444 Comment 4 Edit History
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The issue seems to come from defaulting same-site to lax. Setting `network.cookie.sameSite.laxByDefault` to `false` fixes the issue in Nightly and setting it to `true` in release breaks the site.