Magical healing and potions with a touch of realism can maintain world building while making space for whump and more satisfying/meaningful injury recovery/resource use. So, some ideas for that:
Healing potions that speed up the natural healing process, but require the same energy expenditure from the person being healed (if not more energy) relative to healing naturally. This can look like pulling someone back from the brink of death, but at the cost of weeks of mental and physical exhaustion or extensive sleeping. Muscle weakness or pain that lingers even after the physical damage is repaired.
Healing with a high metabolic cost, making the person incredibly hungry and need way more food than normal. If they can't eat enough to compensate, they lose weight proportionally.
Healing that can mend tissues (broken skin or bones knit back together) but not restore blood volume or reverse other types of trauma (like head injuries).
Energy or stamina potions that have a similar metabolic cost, acting more like an adrenaline rush that blinds the body to pain temporarily but can easily result in overexertion. Maybe it borrows the energy from the future too, so that when the character crashes, it's twice or three times as hard as they would have crashed had they not taken the potion.
Magical healing that takes a toll on the caster, beyond just expending their magic. Referred pain taken on by the healer, bone deep aches that nothing but time can relieve, physical stress and strain, feeling too hot or too cold (symptoms similar to heat stress or other conditions resulting from extreme physical exhaustion), fever, needing to sleep or eat more, weight loss, tiring faster in other activities, elevated heart rate, headache, dizziness, etc.
Potions that have a level of toxicity to them. You get the desired effect, sure, but the plants needed to make it are very slightly toxic. There are strict dosing guidelines to avoid negative effects, but side effects can range from nausea and headache at low doses to full on poisoning (vomiting, passing out, tachycardia, and even death). Different potions have different toxicity levels and tolerated doses.
How long a potion's effects last, how intense it is, how effective, etc can all be influenced by a person's body size and metabolic rate (among other factors), just like modern medicine.
Potions can be diluted by adding water, or strengthened by steaming off some of the water already in it, to various effects. They can also spoil or be ruined by some conditions (heating or cooling past a specific temperature, expiry date, etc).
Different application methods--drinking a potion vs injecting into muscle or into the blood stream vs applying it on a cloth or mixing with gelatin/other ingredients to form a salve or lotion.
Potions that are healing on their own but become toxic if taken together.
Potions that function like modern pain medication--relieving the pain, but at the cost of numbness, fatigue/drowsiness, or altered consciousness.
Magic restoration potions that allow more magic use, but slow natural magic regeneration for a few hours, and may have side effects like a low grade stimulant (feeling jittery or wired, dizziness, nausea, etc). May feel unsatisfying and the magic restored may feel different (less potent? More artificial?) compared to the person's naturally present magic. Maybe it's enough to delay or lessen symptoms of magic depletion, but still leaves them feeling ill or "off" somehow.
