I found crash reports related to this:
Process: XCBBuildService [88276]
Path: /Applications/Xcode-beta.app/Contents/SharedFrameworks/XCBuild.framework/Versions/A/PlugIns/XCBBuildService.bundle/Contents/MacOS/XCBBuildService
Identifier: XCBBuildService
Version: 13.1 (19453)
Build Info: XCBuild-19453000000000000~7 (13A1030d)
Code Type: X86-64 (Native)
Parent Process: Xcode [88227]
Responsible: Xcode [88227]
User ID: 501
Date/Time: 2021-10-25 09:29:58.569 +0200
OS Version: macOS 11.6 (20G165)
Report Version: 12
Bridge OS Version: 5.5 (18P4759a)
Anonymous UUID: A0496C37-F5FE-6AF6-FD23-F367C8D3C235
Sleep/Wake UUID: A2A0FF9D-01E8-4BF6-A887-5F3820ACA4ED
Time Awake Since Boot: 230000 seconds
Time Since Wake: 200000 seconds
System Integrity Protection: enabled
Crashed Thread: 8 Dispatch queue: XCBBuildService.ActiveBuild.operationDelegateQueue
Exception Type: EXC_BAD_INSTRUCTION (SIGILL)
Exception Codes: 0x0000000000000001, 0x0000000000000000
Exception Note: EXC_CORPSE_NOTIFY
Termination Signal: Illegal instruction: 4
Termination Reason: Namespace SIGNAL, Code 0x4
Terminating Process: exc handler [88276]
Application Specific Information:
XCBCore/Settings.swift:315: Fatal error: Couldn't load file type spec file.rcproject in domain macosx
Thread 0:: Dispatch queue: XCBBuildService.ServiceHostConnection.receiveQueue
0 libsystem_kernel.dylib 0x00007fff204c8cce read + 10
1 com.apple.dt.XCBServiceCore 0x000000010ffa95b8 closure #1 in ServiceHostConnection.resume() + 104
2 com.apple.dt.XCBServiceCore 0x000000010ffaa9ce thunk for @escaping @callee_guaranteed () -> () + 14
3 libdispatch.dylib 0x00007fff20352623 _dispatch_call_block_and_release + 12
4 libdispatch.dylib 0x00007fff20353806 _dispatch_client_callout + 8
5 libdispatch.dylib 0x00007fff203595ea _dispatch_lane_serial_drain + 606
6 libdispatch.dylib 0x00007fff2035a0ad _dispatch_lane_invoke + 366
7 libdispatch.dylib 0x00007fff20363c0d _dispatch_workloop_worker_thread + 811
8 libsystem_pthread.dylib 0x00007fff204fa45d _pthread_wqthread + 314
9 libsystem_pthread.dylib 0x00007fff204f942f start_wqthread + 15