I don't believe it should be an AVX2 issue for me. Crashes on startup every time. Tried lowering resolution and opening in windowed mode, etc.
mid-2014 Macbook Pro
2.8 GHz Quad-Core Intel Core i7
This is a Haswell architecture which as AVX2 support
sysctl -a | grep machdep.cpu.leaf7_features
machdep.cpu.leaf7_features: RDWRFSGS TSC_THREAD_OFFSET BMI1 AVX2 SMEP BMI2 ERMS INVPCID FPU_CSDS MDCLEAR IBRS STIBP L1DF SSBD
Process:               Baldur's Gate 3 [1069]
Path:                  /Users/USER/Library/Application Support/Steam/*/Baldur's Gate 3.app/Contents/MacOS/Baldur's Gate 3
Identifier:            com.larian.bg3
Version:               4.1.90.6193 (4.1.90.6193)
Code Type:             X86-64 (Native)
Parent Process:        ??? [1]
Responsible:           Baldur's Gate 3 [1069]
User ID:               501
Date/Time:             2021-02-06 14:57:22.728 -0800
OS Version:            macOS 11.2 (20D64)
Report Version:        12
Anonymous UUID:        2695EAEE-3902-EAD9-2901-A09F8BD1393B
Sleep/Wake UUID:       2D0348D3-3846-4165-874A-B7ED25A2194A
Time Awake Since Boot: 880 seconds
System Integrity Protection: enabled
Crashed Thread:        0  MainThrd  Dispatch queue: com.apple.main-thread
Exception Type:        EXC_BAD_ACCESS (SIGSEGV)
Exception Codes:       KERN_INVALID_ADDRESS at 0x0000000000000070
Exception Note:        EXC_CORPSE_NOTIFY
VM Regions Near 0x70:
--> 
    __TEXT                      100000000-106622000    [102.1M] r-x/r-x SM=COW  /Users/*/Library/Application Support/Steam/*/Baldur's Gate 3.app/Contents/MacOS/Baldur's Gate 3
Thread 0 Crashed:: MainThrd  Dispatch queue: com.apple.main-thread
0   com.apple.GeForceMTLDriver    	0x00007fff64db07f6 0x7fff64c9b000 + 1136630
1   libRenderFramework.dylib      	0x0000000106c6dd98 rf::metal::MetalRenderer::PassSetPipelineState() + 408
2   libRenderFramework.dylib      	0x0000000106c6d924 rf::metal::MetalRenderer::AcquirePass() + 612
3   libRenderFramework.dylib      	0x0000000106cb4aa2 0x106bf9000 + 768674
4   libRenderFramework.dylib      	0x0000000106cb41a1 rf::metal::RendererCommandBuffer::ProcessCommand(unsigned char, char const*) + 1921
5   libRenderFramework.dylib      	0x0000000106cb4d16 rf::metal::RendererCommandBuffer::Submit(bool, rf::GPUFence*) + 166
6   libGameEngine.dylib           	0x00000001071c49f6 0x106e92000 + 3353078
7   libRenderFramework.dylib      	0x0000000106ca29d6 rf::StageGroup::QueueSubmit(rf::IAppStage*) + 102
8   libRenderFramework.dylib      	0x0000000106c9db99 rf::StageGroup::FinishAndExecute() const + 41
9   libRenderFramework.dylib      	0x0000000106c821f9 rf::RenderFrame::FinishAndExecute() + 121
10  libGameEngine.dylib           	0x000000010756b474 0x106e92000 + 7181428
11  libGameEngine.dylib           	0x0000000107322a0a BaseApp::OnIdle() + 26
12  com.larian.bg3                	0x0000000100a53a50 0x100000000 + 10828368
13  com.larian.bg3                	0x0000000100a52bfd 0x100000000 + 10824701
14  com.apple.CoreFoundation      	0x00007fff206c1fec __CFNOTIFICATIONCENTER_IS_CALLING_OUT_TO_AN_OBSERVER__ + 12
15  com.apple.CoreFoundation      	0x00007fff2075d89b ___CFXRegistrationPost_block_invoke + 49
16  com.apple.CoreFoundation      	0x00007fff2075d80f _CFXRegistrationPost + 454
17  com.apple.CoreFoundation      	0x00007fff20692bde _CFXNotificationPost + 723
18  com.apple.Foundation          	0x00007fff21401abe -[NSNotificationCenter postNotificationName:object:userInfo:] + 59
19  com.apple.AppKit              	0x00007fff22ef3b2d -[NSApplication _postDidFinishNotification] + 305
20  com.apple.AppKit              	0x00007fff22ef387b -[NSApplication _sendFinishLaunchingNotification] + 208
21  com.apple.AppKit              	0x00007fff22ef0a72 -[NSApplication(NSAppleEventHandling) _handleAEOpenEvent:] + 541
22  com.apple.AppKit              	0x00007fff22ef06c7 -[NSApplication(NSAppleEventHandling) _handleCoreEvent:withReplyEvent:] + 665
23  com.apple.Foundation          	0x00007fff2142d056 -[NSAppleEventManager dispatchRawAppleEvent:withRawReply:handlerRefCon:] + 308
24  com.apple.Foundation          	0x00007fff2142cec6 _NSAppleEventManagerGenericHandler + 80
25  com.apple.AE                  	0x00007fff264aaed9 0x7fff2649e000 + 52953
26  com.apple.AE                  	0x00007fff264aa5f4 0x7fff2649e000 + 50676
27  com.apple.AE                  	0x00007fff264a3260 aeProcessAppleEvent + 452
28  com.apple.HIToolbox           	0x00007fff289645a2 AEProcessAppleEvent + 54
29  com.apple.AppKit              	0x00007fff22eeae3e _DPSNextEvent + 2048
30  com.apple.AppKit              	0x00007fff22ee9177 -[NSApplication(NSEvent) _nextEventMatchingEventMask:untilDate:inMode:dequeue:] + 1366
31  gameoverlayrenderer.dylib     	0x0000000106b20e9e -[NSApplication(SteamOverrideNextEvent) steamhooked_nextEventMatchingMask:untilDate:inMode:dequeue:] + 76
32  com.apple.AppKit              	0x00007fff22edb68a -[NSApplication run] + 586
33  com.apple.AppKit              	0x00007fff22eaf96f NSApplicationMain + 816
34  libdyld.dylib                 	0x00007fff205ef621 start + 1