If you enable the support mixed text direction setting, the text direction for all post content should get automatically set based on the language. If you have enabled that setting, try refreshing the page to see if that fixes the issue.
Testing this now, I’m finding that the text direction of titles is no longer being correctly set. That used to work:
Interestingly, an old issue that was causing the text direction of the FAQ, Terms of Service, and Privacy pages to not get set correctly has been fixed:
When I tested this in 2018, the text in the box above would have been incorrectly displayed RTL (based on the site’s locale.)