As my title says all about the question, are underarm serves a fair thing in tennis? Because the reaction of Chris Garin says me otherwise when Alexander Bublik served him an underarm serve.
I was watching some YouTube videos where it mentioned 2019: Year of the Underarm Serve because of (Nick) Kyrgios hitting many of them. Even this year it was fairly common during matches. Just yesterday we saw Daniil Medvedev hitting one against Alexander(Sascha) Zverev. In his post-match interview/press-conference, he told that: "I didn't want to disrespect him (Zverev) but my wide serve was not working as well as I would like today and he was returning it good. [...]"
Prior to this, in February 2019, Rafa was rather enraged by Kyrgios's underarm serve. He commented, "[...] He lacks respect for the public, the rival and towards himself."
Why did Medvedev mention the fact that Sascha could have been disrespected because of that serve technique? Also, why did Rafa look at it like a wrong act?