There are many possibilities that can cause this issue.
Could be your permalink setting.
Could be something you define in wp-config.php
Could be something your plugin or you added in .htaccess file.
I can see in your url, there is a word blog,
I viewed your webpage source code, the word blog is not part of your url structure, it’s dynamically generated.
Maybe this is causing your issue.
Please check you WordPress admin -> Settings -> Permalink
Try to use one of available settings.
Please also try disabling plugins to see if this is a plugin conflict.
Sorry, that’s all I can help on this issue.
I am unable to replicate this on my localhost test site.