Why are email attachments not downloading after updating to iOS 18?

Since updating to iOS 18 and subsequent 18.0.1 we have problems on both our iPhones and iPads downloading email attachments, doesn’t matter how small they are, and also we have difficulties forwarding these emails. Really really frustrating when a hospital admission ( pdf document) form is emailed to us and we are unable to fill it out. Never ever had this type of issue before iOS 18.

eventually a 3.5 mb document downloaded but it took forever and we have very fast internet.

[Re-Titled by Moderator]