It seems any photos included in all the emails I am getting, (spam emails, good emails..etc) are being downloaded to my computer

How do you determine photos are being downloaded to your computer? Which folder are they saved to?

When opening a message, it's inevitable contents us being downloaded as part of the message. However, Thunderbird does not extract any images as part of an email, and it doesn't save them to your computers disk.

I'd check the Gmail settings whether Google does the photo upload for you on the server.

The photos start appearing in my Google Photos account. I do not download them to my computer, but when I open the emails, I see the images in the emails, then I see them in Google Photos. Seems when the email it opened somehow they get sent to my Google Photos account.

I have checked all options and settings in google photos and cannot find any way to prevent this from happening. I cannot find anything in the Thunderbird or the Gmail program to prevent that either.

I have matched up many of the photos to emails I have received in thunderbird and do see them on google photo. so somehow they are getting up there.

Seems when the email it opened somehow they get sent to my Google Photos account.

Thunderbird knows nothing about Google Photos.

I have checked all options and settings in google photos and cannot find any way to prevent this from happening.

There's more than just Google Photo settings. I'd suggest you ask in a Google forum about how Gmail and Google Photos are linked. Google settings can be tricky.