Many times tactician can pose a real challenge for anyone , but for that to happen you willl have to forgo the games main features wich is quicksaving, autosaving and reloading . I'm reloading when I stumble into an ambush and half my party get wiped + all the spells and daily abilities you lost for huge setback even if you eventually win , so I reload and ...but I also position myself, buff etc and wops all of a sudden a severe encounter becomes mundane when you know a little of what will happen, she will scream for help, that guy will run for a drum etc etc .. The elephant in the room is reloading and having trial and error combat possible , not much to do about it more than creating a iron man mode
This is not really how the Tactician mode looks like - or at least not so for some of the players. If you do struggle like that, you are not really playing Tactician mode - you are still learning how to play the game.
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In Tactician mode, my party /main char have not died even once yet. Before my first playthrough, I spent over 20 hours slowly learning how to play this game, which was in the standard mode, until I hit level 3. At that time, I did not even know how to deal damage properly, a group of 6 level 2/3 guys were already able to take down my party of 4 - what a shame - when I realized I should use healing potions, it was already too late. After such learning experiences, I started my first playthrough, which is in the Tactician mode only. Even in the most brutal battle so far, which totally surprised me considering how nice I was to my enemies (trying to avoid killing them, which I realized later was meaningless), my party prevailed. It was my party of 4 vs a group of up to 9 enemies (boss was 1 level higher) - Shortly after the fight started, 3 of my 4 guys took turn to be frightened, poisoned, paralyzed, etc., unable to move, attack, or take actions. And the enemy boss was healed to full health at the start of every round. On my part, it was nearly a hopeless struggle... But, the beauty of a game like BG3 is: there is almost always (thought not always) a way out, as long as you look hard enough to look for it. My party won the battle in the end.
I'm still learning - solely in the Tactician mode of course. I play a highly charismatic char, but I hate to avoid combat and almost always try to talk people into fighting me (unless that's really bad roleplay-wise: for example, always a bad idea to be rude to a merchant, unless you wish to kill and robe them). To avoid getting butchered, just don't pick a fight you can't handle at all. When my main char had < 50HP health (the total heath pool of my entire party was < 200HP), the game presented me with the option to attack a guy with a whopping health pool of 520HP!!! There was absolutely no way to not get slaughtered if I had attacked. So, I just convinced them to leave in peace.
Oh, by the way, I don't reload mid-combat. I make saves only for exploring different options or witnessing different cut scenes at a later time.
The Tactician Mode is not really that difficult. The Standard mode is essentially a tutorial of some sort. Once you have learned enough how to play this game, Tactician naturally becomes the updated standard way how BG3 is supposed to look like. Like as in BG1 and 2, there are numerous ways to handle things in the game. Staying alive all the time in Tactician mode may not be easy, but it's not really that hard either. When struggling, always look around trying to find a way out.
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Once players have graduated from the Tactician mode, they naturally wish to have a new level of challenge. Totally understandable.
I'm one of such players. After I am done with my playthrough (which is on Tactician), I hope there will be a new level of difficulty awaiting to explore further.
