only sub directory website does not work Redirection

I use Redirection on top directory and sub directory.

for example,

https://www.example.com

and,

https://www.example.com/blog/

These two websites are completely different website. so, I have to use the plugin on each website.

Top directory website is 100% working fine.
But, on sub directory website, there has a REST API ERROR.

Please check this picture.

If I click

/marriage/wp-json/

a lot of codes are listed.

But I got REST API error.

Please help me to fix this problem.

By the way, Site Health is “Good” and I tried all plugins are deactivated and use default theme of WP.

Best Regards.