Is BG3's tone different from the past games? ABSOLUTELY but thats because they aren't the same people who made those games and Larian was smart and made sure to distance its story from the originals.
If you played any recent module from 5E then you'll know for sure that BG3 is as in line with Forgotten Realms tone as you can get.
I didn't play any recent module from 5E, because, oh surprise, I am a Baldur's Gate fan, not D&D 5E fan.
And as it was mentioned many times before if Larian wanted to distance themselves from BG1&2 they shouldn't have called Baldur's Gate3 a Baldur's Gate3. You can't have a cake and eat it too.
Baldur's Gate: Dark Allience wasn't called Baldur's Gate3 God of War (2018) isn't called God of War4 Tomb Raider: Legend and Tomb Raider (2016) both don't pretend to be direct sequels to previous titles. Upcoming Avowed from Obsidian is called Avowed, not Pillars of Eternity3 Gears Tactics isn't called Gears of War 6. DMC: Devil May Cry wasn't called Devil May Cry5
WotC and Larian willingly branded the D&D 5E project as a direct sequel to BG1&2. As much as I hate gaming convention of naming reboot like the first game, at least it helps to diffirenciate series. Lets say someone in the future will make BG4. What universe will that game take place? BG1&2? BG3? It is just unnecessarily messy and IMO bad branding. Baldur's Gate3 means little to people who don't care about BG1&2 and will annoy people who adore the IP.
As a side note, a claim that devs are incapable to do different tones is absurd. If they only do what comes naturally to them then they are poor craftsman. Just as Alien: Isolation was praised for how well it adapted Alien IP, one can judge Larian on how well they adapt Baldur's Gate IP. If their intention was not to adapt BG IP, then from my perspective as a fan, they should have left it alone. I even doubt if they are interested in adapting D&D 5E, considering how they insist to change many aspects of it.
