Glaring health and mana potions problem

I am going to assume you guys already know that hp potion and mana potion stopping once you hit full is a problem. I am assuming you know all about it, and decided despite the huge problem, that this made more sense in the grand scheme of things. Well, it doesn't. At all.
The fact that hp/mana potions stops when you hit full doesn't make any sense from any standpoint. Here, let me demonstrate, you drink a potion that gives you 100 over next 7 seconds, that potion gets inside you, now that potion isn't going to magically go away once you reach full health, it just won't, it doesn't just fade away, it will keep increasing your health, except you can't get any healthier. Same idea with mana. Those should keep rolling.
Furthermore, the bigger part of the problem is the roll on your flasks, you are wondering why people don't use more than 1 hp flask and all utility flasks? Well, there is a big factor in the idea that losing your shock/bleed/freeze/curse immunity when you hit full hp is scary as fuck and wildly unreliable. At least, at the very least, make the immunity be the same duration as your flask, you have a 10s hp flasks, you hit it, it gives you the immunity for full duration regardless of the hp gain.

You made it work for life leech, I don't see why flasks should be any different. Plus this would help your health flasks be more helpful and actually used. I really think your health flasks needs some love to make them compete with utility flasks, you guys went way overboard a while back creating all these utility flasks, that really hit the life flasks hard, and making them keep on rolling while full hp would help bring back some balance.

TBH it should have been changed long ago. But it should be working similar to burn: you can use multiple flasks, but only the most powerful regen takes place, and they all tick down in duration at the same time. Also, using flask again resets it duration, wasting all the remaining heal.

I dont agree. in fact, I want to go back when all flasks simply dispelled the effect and didnt give immunities. 10s immunity to an ailment on one out of 3 flask charges ? might as well not have that in the game then if you can just have perma-immunity.

the problem with having flasks continue through full hp is that they become a form of [always-on] regen. same with mana flasks because it allows you to just tap a flask ones and just spam spells

think about how slayer leech is so powerful in lab. now think about what it really is. its leech that doesnt stop at full life (and yes, leech DOES stop at full life), ie 20% regen/second

if this is to be done, flask values would have to be drastically reduced. 1k life regen isnt really meant to be up 100% of the time. nor is like 200 mana/second without investment on top of your existing mana regen

I don't use health or mana potions for just these reasons.

The magic flasks are very useful for the second effect, such as Staunching or Warding, and these are utility-style effects. Naturally a player wouldn't want their utility effects to cut out because of some side reason, like their health hitting full, so health and mana flasks just become more of a liability than anything.

Plus, speaking just for myself, I've gotten very used to running 5 utility flasks. I made this transition to all utility because I turned to Chaos Innoculation for every single high level character I had (ranger, shadow, scion, witch) because it just fixes so many problems. Even with the Energy Shield rebalance, I'm using stuff like Sulphur Flask with Zealot's Oath for a "healing potion". (The fact that Sulphur Flask heals nearby allies like Catarina minions and the Elreon relic is a bonus.)

Even levelling up a Slayer, I've stuck with 5 utility flasks as soon as I had the crazy life leach going. The Life flasks don't heal fast enough in the later stages when you can just get blown up in a second by some OP mob attack or a spike. The only way I can see a Life flask competing as a viable "staying alive" option in the later stages is for that potion to keep restoring your life for its full duration.

In the end, the current Life flasks just don't viably compete for a slot over a 5th utility. A ton of regen and leech is just better.