Please find a way to prevent companions from wandering into AOE spells after combat. Maybe figure out a way to have them avoid traps as well.
The easy fix is to dispel AOE attackl spells when combat ends. The hard fix would be to fix the pathing issues that cause companions to keep committing suicide
by walking into Acid or Cloud of Daggers at the end of combat before they can be dispelled or cleared.

Just keep a cantrip that requires concentration and cast it at the end of battle. One time I had party members walk into a spell I had cast and it's never happened again through 6 playthroughs. It's a you problem if it keeps happening. Sorry.

If it's a concentration spell, you can cancel it yourself anytime, select the character that is concentrating on it, and down under the portrait on the left there will be a little icon with an x, hit the x to cancel concentration.

Some acid and poison aoe effects don't actually cause direct damage, they will just inflict you with a status, but the game seems to have difficulty managing npc pathing for things like this. I've had companions refuse to go into a non-damaging poison cloud, but then walk into fire on the ground and take damage.

Unchain your party during combat. That way after the combat is over they won't go running to get back in order. Each will stay where they are so that you can control the situation.

This problem has been around since like forever.
Clicking RMB helps. Sometimes.

The easiest solution would be for the game to stay in turn-based mode if there are any effects in the area with a duration measured in rounds.

This should cover most surfaces and area effects, but it would also cover things like short duration effects you might want to make use of before they end, such as Warden of Vitality.

This should also be extended to count the round after combat ends as still being combat, so that combat-only effects can be triggered, for example a Wildheart Barbarian's Bear Heart Unrelenting Ferocity; it's an action so of course I'm never going to use it in combat when potions are bonus actions, but it's also tied to Rage so immediately ends when combat does so you can't use it as a final round top-off unless you purposefully keep one enemy alive so you can use it.

Obviously improving the allied AI would be the most correct fix, but their being dangerously suicidal has been a problem since early access, just wait until you're trying to keep Jaheira alive in the assault on Moonrise Tower, or the Gondians at the Steel Watch Foundry (I swear, they are absolutely determined to die, literally charging and teleporting into steel watcher self-destruct areas faster than I can shove them to safety). They buffed Jaheira's hit-points to try to make her less likely to kill herself, and my impression is that that's the best we can really hope for. Though if they just gave us control of the allies it would solve so many problems with them.

That doesn't work. Combat ends and the spell is still up, possibly from 2 npcs. The group immediately reforms before there is a chance to click on each spellcaster and individually cancel the spells. Frankly it should not have been a problem in the first place. Larian really has no excuse for not fixing this Quality of Life issue. As far as frequency, they almost always get damaged walking into them but rarely die outright. So it's a reall pita when it happens.

You're the guy killing your party members but I'm wrong. There are multiple ways to prevent this from happening, try some of them. Is it really that hard to separate your group so they don't run to each other? Click to turn based mode after battle, you know when the battle is going to end. Maybe just position your team better before using these types of spells.

I know it can be a problem early on as you're learning the game, but in fairness Vua is right. There are ways around the problem that work. I don't remember the last time I had a problem with this.

Stop making excuses for the Developers. You as a player should not be doing extra work to account for a games shortcomings. It is already a pain to click through characters to cancel concentration spells. If it is an attack AOE concentration spell it should be an option to auto-dispell at the end of combat. Or at the very least don't have the party regroup automatically until a movement is requested.

I don't see it as an excuse for the developers. You know the party regroups if chained together. You know they don't if they're unchained.

Click one button and everyone unchains. Or leave them together. Either way, it's your choice. You know the results of your choice. It's not up to the developer to make that choice for you.

I wish there was a way to remain in turn mode at the end of combat rather than automatically exiting turn based mode.

It’s not just regrouping (which can sometimes be mitigated) but it would also be handy for remedying conditions picked up during combat more efficiently.

Not a game breaker but just a personal preference.

As for pathing and the movement mechanic in general it is what it is. In other words it ain’t going anywhere.