Normally when trading with villagers, they can only restock their trades 2 times per day whenever they work on their profession.

Ever since the 1.14.4 update, that buffed their trades and can work all day even when they don't restock, they actually will restock whenever they do their work after their trades are fully locked after 2 times.

To reproduce:

1. Get a villager with a profession (Any profession)
2. Lock his trades (Must be day time)
3. They will work and do their 2nd and final restock (As it normally works)
4. His 3rd work (after all the trades are locked after 2 times per day), it will continue to restock non-stop till it almost gets to the sunset.

Sorry for the weird explanation, but thats what I have been experiencing.