Why does my Mac keep suggesting a correct word is spelled incorrectly and suggesting a wrong spelling?

I've had a running issue I can't figure out. It seems to mainly impact the Mail program on my Mac. When I type messages, it will underline words that it says are spelled incorrectly...but they are correct. When I click to look at their suggestions, it will suggest an incorrectly spelled word.

For example, I correctly typed the word "simple" in an email, and it was underlined as incorrect this was proposed.

These are not words that I mistakenly added to my dictionary at some point. It happens often with all sorts of words.

How do I fix this? Thank you.