TestRunnerSRL
Softlock possibility with the new feature of paying before obtaining a scrub item
Saying "Yes" to a scrub when getting his item apparently sets the flag for the scrub item to be obtained. However, if the scrub area to speak to him is bigger than the area where you can obtain the item, you can walk away without getting the item. If you happen to reload the area, the scrub is gone and you'll never be able to get his item, even though logic thinks you already got it.
Tested and confirmed on Roman's branch, v8.1.47 R-1
The example you gave on Discord was the Deku Tree MQ Deku Scrub location, where you can talk to the scrub from below but can't actually get the item unless you're on the ledge. One proposed fix was to use the delayed item queue for scrub items but that would have logical implications in this case, as you would then be able to get the item from below. Maybe instead, the radius for talking to the scrub can be changed to match the get item trigger?
In vanilla, it seems to be the same problem. I just tried it with the Deku Tree MQ scrub again. In vanilla, the scrub is infinite, but I was able to stun him from below, buy his Deku Shield and didn't get anything. If I now get onto the ledge and close enough, I get the shield and pay the 50 rupees. But if I reload the area, the scrub just resets and continues attacking me.