So, more often than not, a lot of balance changes I see for Pip, but more often than not, they never seem to be something that would actually be good for the character. There are some changes that, on paper, might sound like a good idea, but with actual execution, wouldn't actually be a good thing. Additionally, Pip has always been in a bit of a weird spot: He's a support champion, that can be played as a full fledged support, but can also deal decent damage to boot and can be considered a full-fledged DPS in addition.
However, there are some small things I would say to change, even as a person who plays Pip. For the most part, he is rather balanced, with some huge issues that he has: For starters, his hitbox. They gave him a visual redesign a while back, and his original design was was a lot taller in comparison, and and even had a larger head. This hasn't been changed, and this really does need to be addressed. It feels like it's literally double his size. Additionally, with the removal of Mischief, cards like From Above should be brought back to their former glory: Pip usually gets the short end of the stick with changes like this, hell, they even renamed a skin he had due to Strix getting a skin with the same name.
However, I'm just gonna list some changes that could be done for each playstyle.
DPS (Catalyst):
For starters, the damage buff is a little too much, but at the same time, not by a long shot, It's one of those things where it is only a little bit overtuned. It currently sits at a 40% damage buff, which is a tiny bit overdone in my opinion, but it only needs a tiny change, roughly 5%, so instead of 40%, 35%.
In addition to this, a change to Moxie might not hurt, maybe making it it instead 8% per level instead of 10%, this way it won't be too intense of a change.
One final thing for a potential change to Catalyst, is to make it add an additional second to the cooldown of Healing Potion and Weightless. This way, it would make the sustain a bit rougher if you can't secure any assists or kills, and would make it more rough for him to safely go in and out of a fight to secure kills, which is in my opinion, a big reason as to why Cassie is rather dumb in the DPS department.
Support (Mega Potion):
The biggest issue with this talent, is just how loadout dependent it actually is. In my opinion, just like Catalyst, this talent only needs a tiny bit. A single second being reduced from the cooldown of Healing Potion would make this feel a lot better to be able to consistently spread your potions out more, in addition to just making the potions more consistent in general.
Another smaller change that could be done, is to increase the radius of healing potion by a small amount, such as 5% or something.
Another thing that really does need changing for this, is to simply make Pep in the step useful. It currently is a dead card that shouldn't be in any deck (much like Sturdy, but story for a different time). Way back when, this card used to be able to speed yourself up as well, and lasted for 2 seconds. Decent, not great, but decent. One change I thought could make this good, is to increase the base speed buff, say 20%, with 2% per level after, making a 30% max increase with Pep in the Step 5. This way it can actually be a decent filler, instead of feeling like a waste of a loadout slot. Remember, before you say that would be crazy, you have to realize that other champions can do a similar amount, can safely add points to the card, and do so for a much longer duration (Pip's is 1.5 seconds, and was a stealth nerf that was done when they said it only made it not affect Pip any more).
Hybrid (Combat Medic):
Now, Combat Medic does need some love. There is a lot that is wrong from this talent, and some good idea was made with it. A talent that forces you to be firing more, and should, theoretically, enable your teammates to be a bit more aggressive with 600 HPS with a 1200 burst heal. However, the big downside to this, is that you don't generate ult charge from healing with your launcher, and you don't get out of combat. Some changes for this are kinda simple (the first to change how out of combat healing should work: If you don't deal damage with a weapon shot/ability, your timer shouldn't be reset). Additionally, an idea I had for this was to make it apply Healing Potion card effects (save for Reload) on every other shot. Pep in the Step and Gift Giver should be obvious. Medicinal Excellence however, would increase the AoE for the healing part of the potion (with a Healing Potion explosion visual being present), but not the damaging part of it. Additionally, sucessful heals generate 1% ult charge per ally hit. Why so little? Well, you can hit multiple allies with it every other second, as well as dealing damage, and healing with healing potion gives about 4-6% (give or take).
These are just my opinions, so feel free to leave feedback and what not.
Also, my signature is out of date, and I'm too lazy to recreate a thread about Pip bugs, so when I'm feeling up to actually doing that, I may just fix it.