That's possible - you can swap bullet types by scrolling with the mouse wheel. They have different uses: the second type launches enemies up, the third homes in on enemies and stops them in place for a bit (or other effects, depending on your powerups). If you didn't realize that, I can 100% see how you could get soft-locked - which leads back into the main problem (mechanics not clear enough...)
If you don't have a dedicated mouse wheel, im so sorry i really shouldve added hotkeys
They also all reload differently: normally, the first bullet type is a typical reload (use all bullets, wait and get them back), second is a charge (slowly charges up while active), third is consumable (you randomly get them when killing enemies).
When you get Random Bullets, it shuffles the way you reload each bullet when you change rooms. It's kinda a debuff (as you put it), but it can allow you to use the more limited types more often - so I felt like it was balanced in that way. Plus, it adds some spice to a run 😉