iPhone will not accept correct email password

When I got home from holidays my email would not download - the message was that there was something wrong with my login. This has happened before and I just put in my email password and the issue is resolved. This time however it did not clear the issue. I changed my email password successfully I.e. I can access my email via safari. I deleted the email account and set it up again. When I put in the password during set up, it initially accepts it but then returns that set up screen with the password field blank. When I put in the password again the “next” button is greyed out and all I can do is cancel. This week I upgraded to iOS 17 and then 18 - and that is I believe the cause. Anybody come across this?