Can I use any link in buyer requests? (Fiverr)
Ans: No, What fiverr says, no one (sellers) is allowed to share any kind of link in buyer requests (while they are replying buyer requests). Even They are not allowed to share any portfolio links as well.
Fiverr strongly prohibiting sharing gig links in their buyer requests while replying for it. Because they are not supposed to promote their services to the buyer. They need to stick to the point.
Choose a gig while replying to a buyer request relevant to the topic and send a plain text without any links.
But fiverr suggesting you use portfolio links at your profile and gig descriptions and if a buyer really wants to see your work, you may refer them to that descriptions just by requesting them to visit your profile and check your previous work samples.