Try thinking about it in the abstract.
***Disclaimer: That change is a terrible idea and I would never even think about implementing it, but I’ll play along just cause I am bored.
So first let’s just start by saying, even if I were to consider making this change(which I wouldn’t), at the bare minimum I would change your proposed change to stop at 5th level spells. Giving long rest casters back spells is stupid to begin with but giving them back 6th+ level spells is just insane. Your proposed change has casters, that only get 1-2 max slots of each level 6th+ to begin with a way to get back 1 slot of each level on a short rest. That is just stupid, plain and simple.
But ok, so you implement your change anyway. First you will need to look at the short rest classes and rebalance them as your change has left them in the dust. So just looking at the low hanging fruit, Warlocks(a short rest class) and Paladin (a half caster), both vs wizard, to start. Let’s assume 6-8 encounters and 3 short rests per day. Let’s look at lvl 10 (I try to avoid ever looking at lvl 20 as rarely do games ever get there and lvl 10 is a good point where most classes have a good number of resources.
Before the change:
Lvl 10 Wizard spells- 4-1st, 3-2nd,3-3rd,3-4th,2-5th for a total of 15, then add 1 5th level slot for Arcane recovery. So 16 slots of level ranging from 1st to 5th per long rest.
Lvl 10 Warlock spells - 2-5th to start and 2-5th level slots per SR for a total of 8 5th lvl slots per long rest.
Lvl 10 Paladin spells – 4-1st, 3-2nd, 2-3rd for a total of 9 per long rest.
After your change:
Lvl 10 Wizard spells- 4-1st, 3-2nd,3-3rd,3-4th,2-5th for a total of 15, then I would assume Arcane recovery goes away and is replaced by this new change. So, PB of 4 means they get 1 of each 1st,2nd,3rd, and 4th x3 short rests. So, in the end the Wizard has 27 slots, 7-1st, 6-2nd,6-3rd,6-4th,2-5th
Lvl 10 Warlock spells - no change, 2-5th to start and 2-5th level slots per SR for a total of 8 5th lvl slots per long rest.
Lvl 10 Paladin spells – 4-1st, 3-2nd, 2-3rd to start plus with PB 4, 3-1st, 3-2nd, 3-3rd for a total of 18 per long rest.
So the Wizard went from 16 to 27 slots, the Paladin from 9 to 18 and the Warlock stays at 8. So you have massively increased the power of half casters, significantly increased the power of full casters, and the Short Rest classes like Warlock and Monk, and ALL melee classes stayed the same.
To start I feel like you would have to tweak your rule a bit to maybe only let half casters get spells back up to half their PB to better keep them in check. Then you are going to need to increase the warlock’s number of slots, I would say double.
You will have to similarly look at classes like Monk and review their resources and increase them to balance, as like warlocks, they have limited resources refreshed on short rests so fall well behind in this new power curve.
Then there are the rest of the melee. You would have to review each classes resources and tweak them upwards to get them back in balance. Some classes will be more difficult than others, but your change has greatly increased full and half casters, roughly doubling their power, so the melee will need tweaks to balance.
In reality, you would have to rebuild every class to some degree, this is a very bad idea. Alternatively, if you are just looking to make Full and half casters into a Short rest classes like warlock, rework their spell slots by level table to cut them roughly in half for spell levels 1-5, then have all slots up to and including 5th level reset on a short rest. 6th and above don’t reset. Would still take some testing and tweaking but is a lot better than blowing the power curve out of the water and rebuilding the entire game to try to find balance.
Just my 2cp