If you're sure they've given up, there's little point in chiding them. They're probably AFK rather than staring at a screen for 8 mins. Alternatively, if they haven't given up and are looking for a way back into the game then you'd just be irritating them. You could report for stalling / bad sportsmanship while you're waiting for the match to end.
Chess Etiquette: When players quit
GothemChess got auto loss when he thought for 90 seconds in a 3/2 game on live stream. I watched the video. He is 2400 and his opponent 1400. He was explaining his plan to us when chess.com automatically declared he abandoned the game.
I have thought hard when under attack, and found an escape. My opponent thought checkmate was forced and that I was stalling, but later said he had not considered the move I found. Had I not found that move, he would have really suspected I was stalling that whole time.
I play around the 850-900 level. I often find when players fall behind in material, instead of quitting, they let time run out, forcing me to wait 8 minutes until the time runs out. I sometimes ask them to move, and sometimes say things like, "come on, don't be a bad sport." But I'm wondering if I'm committing bad sportsmanship by doing this. They have 10 minutes to make their moves, and if they want to "think" for 8 minutes, well that's what I signed up for. Am I being a bad sport?