Glint only shows up if they are looking down a scope while aiming at you. In this guide, you will find out all the glints in Halo Infinite.
Blue-White with lens flare-Shock Rifle:
A white-Yellow horizontal line with a diamond in the middle- Sniper rifle:
Red rhombus-like – Stalker Rifle:
White Wide X-Commando Rifle:
Regular X-Battle Riffle:
Big Red star-Skewer:
Orange brackets with Dot in the middle- Havdra while lock-on is engaged: