That possibly is not the case unless you have attempted to change the whole structure of your website like editing tens or hundreds of your previously indexed web records that might cause some problems in certain cases. You know, many times it is better to leave things alone, especially when a ton of pages have already been indexed and accessed by Google because sudden changes in web structures might cause temporary drops.

If you have added new content pages to your site and have used a couple of bold plus italics, that is nothing to worry about because such styles are being used by thousands of people everyday and the impacts on ranks are minimal if not positive. Maybe the cause of ranking drops is related to something else like your website being recently launched, not having many content pages or links or many new links have been added to that quickly.

It depends on how you often build links or how often Google visit your site the better the links the better.