Is anyone else having problems with their Tesco password??. I have had to change mine three times this weekend, and when I try to log in again it says it isn’t recognised.
If possible, try using a different device. (e.g. if you've been using an iPad, try from a mobile phone, laptop or desktop computer).
If the problem then vanishes, you'll know that the problem lies with your original device (or with Safari on that device).
If the problem persists, then clearly it's a fault with Tesco's system, meaning that you'll need to contact their customer service team to get it sorted out.