Red Hashtags - indicate that your post was not found on that particular hashtag page.
Red Strikethrough Hashtags - indicate that this hashtag belongs to the list of hashtags that has been banned by Instagram
Triberr's Shadowban Logic
Firstly, the tester is a guide and not necessarily absolutey fact. That being said, there are two methods to consider here:
Test Tool's Method:
The tester checks the post's meta data for each hashtag used on a post. If any hashtag is missing from the source code of the post's page URL, then the test fails that hashtag. This is the best programmable method we've been able to determine thus far related to whether a post is getting full visibility within hashtag search results. It's not perfect, but it's better than nothing.
Ideal / Perfect Method:
Check Instagram hashtag search results directly for a specific post from an account that does NOT follow the account you're reviewing. If the post is visible, then it's fine. If it is not found, then it has been suppressed / shadowbanned.
Of course, this is a more cumbersome approach as some hashtag search results are in the millions of results. Unfortunately, Instagram does not offer its API to perform this search programmatically.
NOTE: In some cases, even we have seen that a post with a hashtag that our tool has flagged (because meta tag is not in source code) may still be visible in the hashtag search results. Meaning the tool did it's job correctly and meta tag was missing from post's source code, yet the post was visible in search results. Not perfect! Hence, use the tool as a guide not as fact.