SharePoint SPFx WebPart and Data AzureWebsites

Hi, we have developed a SPFx WebPart and we use Azure Functions to connect to API. When users opens site with webpart there is pop out windows where he logs to his account and this functions call external API. Weird situation started few days ago when this funciton stopped working on IOS SharePoint app. On Android it works well and Windows. Do you have any ideas why it happens ?

Best regards

Kamil