Their comments on your posts may be visible only to them and not to others
You may not see when they are active or if they have read your messages
Their replies to your stories may go to message requests or not appear normally
You may still be able to message them, but their responses may seem delayed or hidden
You may not see their online status or activity status
Their likes and comments may appear less often or inconsistently
You may notice their account interactions with you seem limited compared to before
You can check from another account to compare whether their comments or activity are visible
Restriction is not always obvious, so none of these signs alone confirm it with certainty