Its hard to even recognize the relation to 5e at this point
What about it makes you think this? The classes, the character sheet, the skill checks, the abilities, the action economy, the spells etc are all in pretty close alignment to 5e. There are some changes because there was going to have to be in adapting a tabletop to a video game where you can't program in DM judgement or the full scope of player creativity. I wouldn't say they're so great as to make the game unrecognisable. Some classes clearly need more pass over (like the rogue), jump and disengage should be separated out, the DC calculation is a bit confusing but adds up to the same thing. Other than that the only significant changes are with the combat where they've replaced the idea of 3/4 and half cover with elevation, and added environmental effects presumably in an effort to give tools for players to be creative.
Aight, lets start with action economy.
Some of the core aspects of combat are missing and some of the changes to the classes are really bad.
[Action Economy Stuff] [*]Dodge Action is missing [*]Disengage is a bonus action for everyone [*]Ready Action is not present [*]No idea why "Dip" has a dedicated button in the UI [*]Shove is an action and not a bonus action, this change severly lessens the impact of the Shieldmaster Feat [*]The Help/Aid action does not confer advantage
[Classes] [*]Rogues, you are aware of it so no need to repeat it [*]Abjuration Wizards were nerfed for no apparent reason and the spells meant to fuel their ward ability are essentially gone [*]No ritual casting for any of the classes [*]Druids die when their wildshape is defeated [*]Warlocks Hex now lasts till the next long rest, Warlocks should get their spell slots back after a short rest, hence why they only have so few
[Spells] [*]Several spells integral to base 5e are missing (Shield, Spiritual Weapon etc) [*]Several were altered to allows for a surface interactions that were never part of the combat system in 5e. Don't get me wrong spell like Minor Illusion are great but are too complex to be fully implemented into a video game but Mage Hand not being able to trigger traps, loot inventories, but able to "shove", please. [*]Spells like Find Familar have been completely changed and the abilities of the familars have also been changed.
I can go on and on, but the easiest way would be you checking out Solasta then boot up BG3 and tell me which one plays more like 5e.