Is that version installed on computer ?

Are you sure this is Thunderbird - many people do not realise they may have Anti-Virus or other updater software checking for updates for programs on their computer, although it is less likely they would be trying to update something that old. Is it possible you have some updater software on computer which is controlling updates or even something you do not want which is saying it wants to download Thunderbird but it's not what you think?

I would close all programs, restart computer in 'Safe Mode' and run a full scan.

Please read: https://blog.thunderbird.net/2023/10/ransomware-alert-are-you-using-a-trusted-version-of-thunderbird/

...to open Thunderbird version 7.2.2.2. This is an old version.

A version that never existed. https://www.thunderbird.net/thunderbird/releases/

There were Tb 7.0 and 7.0.1 Releases.

Thank you James and Toad Hall. I note from James that this 7.2.2.2 version is not legal and I did try the scan. Nothing was shown in Winit and I still get the message. I will continue to delete, just a small pain. Thanks again to you both. Colin