Welp, time to make another post about this. I reported this back in March and bumped the thread twice, but this bug is still in the game lmao. The old post is here: https://forums.focus-home.com/topic/37006/might-as-well-make-resupplying-instantaneous
Basically, if you stand next to a resupply box and enter the Loadout menu, and manually click the "Resupply" or "Save Loadout" buttons with your mouse (don't use "Esc" or "F"), you resupply instantly. Extremely useful on Frenzy so you can get your health and ammo back before a bot knifes you in the back or detonates a suicide vest.
This exploit doesn't work in Hardcore Checkpoint, probably because of how the limited resupplies were set up.