Inline code blocks don't format when the content is pasted.
When you type a backtick (`), then paste text, and then type another backtick the text does not get formatted as an inline monospaced text block.
Joel Day commented
I truly cannot comprehend how Microsoft, with 150,000+ employees, could be using Teams and not fix this.
Yep, this is super annoying. I run into this all the time.