Thunderbird lying about viewing message body as plain text

[WhatevaYeah]

Hello

Thunderbird version 102.10.0 (64-bit) is lying to me. I told it to view the message body in plain text, but its not really showing the message body in plain text and is instead altering it without notice. Please see a screenshot of the problem:

https://i.ibb.co/nmbhqSx/Untitled.png


I tried changing the preference 'mail.display_struct' to false, but it didn't fix it.

How can I fix this problem?

Thank you

[WhatevaYeah]

I don't know how I managed to explain my problem so bad.

To clarify, in the image, the text on the left is Thunderbird's so called 'plain text', whereas the text on right is the actual body of the text that was sent.

I want Thunderbird to show the actual body of text in e-mails that I view.

[DanRaisch]

More context needed here. Is that an incoming or outgoing message. Nothing seems to be altered but only formatted as the part on the right looks like an HTML formatted page displayed in a text editor.