Not all my emails are showing in mail

I have recently purchased a new iPhone and my iPhone mail is playing up. I have three accounts. One Gmail -works correctly and two Bussiness imap accounts linked to my domain. One account is correct and shows all mail but my main mail account only shows a portion of my emails. It seems random as to what shows.

When on my computer in Thunderbird all my mail shows.

When I cross reference that with my iPhone there are lots of emails. Some ‘read’ emails are missing and some ‘unread’ are also missing.

I have the latest iOS 18.1

Can anyone help