Is Excessive Gig Sharing & Marketing is the main reason for decreasing Impressions and clicks?
Impressions and clicks are an on-site metric only. Impressions are only gained when someone searches for your related keywords, and your gig shows up in the search result. Clicks are only registered when someone, on Fiverr, clicks your gig image, usually in search results or category pages.
If Impressions are dropping, that means fewer people are searching for, or seeing, your gig in gig searches. If clicks are dropping, that means that fewer people are interested in taking a look at your gig.