I honestly don’t blame them for leaving trial matches, it’s filled with a bunch of subhuman losers who like to abuse the most overpowered slop to make up for their lack of gunplay skills
Depends on when they leave. Both comp and trials have loss protection if you lose a team mate at the start of the game but if they leave later that protection does not proc anymore or it'd be abused (more than it already is).
As a solo player you also get loss protection by default both in comp and trials if you match duos or trios.
You don't. Comp have the same quitter protection as Trials. Maybe he left later in the match. Only quitters in the first 90 seconds or so (don't know the exact threshold) count towards the protection.