This buff is practically nothing.
To put it this way. Imagine Moira’s LMB has a clip of 90. She uses 10 ammo a second, and when she uses her RMB, she regenerates 10 ammo for every second her beam is connected to an enemy,
Moira also, passively regenerates 2 ammo per second, and this passive regeneration is getting buffed. 20% buff puts her at 2.4 ammo per second.
So in other words, if Moira was to regenerate her entire LMB’s “clip” without using RMB, currently it would take 45 seconds. With the buff on live, it would take 37.5 seconds.
If you use your RMB, it takes 9 seconds.
It’s technically a buff, but practically it doesn’t increase her power at all. It takes 25 seconds for her to generate 1 second extra of LMB compared to live.