Go to this website : https://faceitfinder.com/
Enter your profile link
you'll be able to see trust factor :
0-7% red
7-14% yellow
above 14% green
Getting reported for cheating/hacking can lower your Trust Factor.
It seems you can retain a Green Trust Factor by getting commended. Remind other players to give commends if you feel like you deserved it.
CS:GO is taking steps against toxic players and besides degrading your Trust Factor, you could even receive a game ban from it even from Casual.
If you're getting kicked for griefing or other obvious reasons, great!
Otherwise, asking your teammates to kick you just so you could abandon a game without receiving a cooldown will also degrade your Trust Factor.
I haven't confirmed this but I heard doing some Overwatch cases legitimately can bring your Trust Factor back. I personally doubt it but feel free to try it out yourselves.
This one's weird but my friend just had to restart his game about 3 times before his Trust Factor turns Green again. Doesn't work sometimes.
Try playing Casual, Deathmatch or other casual gamemodes until your Trust Factor goes Green again. Your Trust Factor can still be affected in casual gamemodes.
Newer Trusted Mode is now enabled by default in the latest update. And a new launch option, “-allow_third_party_software” lets third party software to access the CS:GO game process