Same issue here. Happens around 5-10 times a month when I connect external Dell U2719DC monitor via USB C: panic(cpu 2 caller 0xffffff801669edf6): [kext.kalloc.2048]: element modified after free (off:1672, val:0xfffffffe00000000, sz:2048, ptr:0xffffff937592b800, prot:zero) 1672: 0xfffffffe00000000 Backtrace (CPU 2), Frame : Return Address 0xffffffa0e2052cf0 : 0xffffff8015e8cfdd 0xffffffa0e2052d40 : 0xffffff8015fd3fd3 0xffffffa0e2052d80 : 0xffffff8015fc45ca 0xffffffa0e2052dd0 : 0xffffff8015e31a2f 0xffffffa0e2052df0 : 0xffffff8015e8c7fd 0xffffffa0e2052f10 : 0xffffff8015e8caf3 0xffffffa0e2052f80 : 0xffffff801669cdca 0xffffffa0e2052ff0 : 0xffffff801669edf6 0xffffffa0e2053470 : 0xffffff8015eeb976 0xffffffa0e20534e0 : 0xffffff8015e9c5ec 0xffffffa0e2053530 : 0xffffff80165ada32 0xffffffa0e2053550 : 0xffffff7fb02fefe2 0xffffffa0e2053600 : 0xffffff7fb02ff672 0xffffffa0e2053640 : 0xffffff7fb02bfc62 0xffffffa0e2053660 : 0xffffff7fb0bf9e78 0xffffffa0e2053900 : 0xffffff7fb02c0800 0xffffffa0e2053930 : 0xffffff7fb0bfb074 0xffffffa0e20539c0 : 0xffffff7fb0bf90f7 0xffffffa0e2053a10 : 0xffffff7fb0bf8ee7 0xffffffa0e2053a60 : 0xffffff7fb0bf7f99 0xffffffa0e2053aa0 : 0xffffff801661d67e 0xffffffa0e2053af0 : 0xffffff7fb02c04be 0xffffffa0e2053b20 : 0xffffff801662792b 0xffffffa0e2053c80 : 0xffffff8015f7f7d1 0xffffffa0e2053d90 : 0xffffff8015e9265d 0xffffffa0e2053e00 : 0xffffff8015e68cd5 0xffffffa0e2053e60 : 0xffffff8015e801e2 0xffffffa0e2053ef0 : 0xffffff8015fa869d 0xffffffa0e2053fa0 : 0xffffff8015e32216 Kernel Extensions in backtrace: com.apple.iokit.IOAcceleratorFamily2(442.9)[065DAA9E-DE99-3C6D-A8D6-06BFD26CA1DC]@0xffffff7fb0bb4000->0xffffff7fb0c1efff dependency: com.apple.driver.AppleMobileFileIntegrity(1.0.5)[A994AEFE-3919-310E-A2C9-405E864BCB7B]@0xffffff80174c0000->0xffffff80174d5fff dependency: com.apple.iokit.IOGraphicsFamily(585.1)[240F08CD-4BC4-3093-8832-0E899EFC14F4]@0xffffff7fb0d35000->0xffffff7fb0d63fff dependency: com.apple.iokit.IOPCIFamily(2.9)[4E85D41F-6AD7-3C24-911C-A8B80B599F86]@0xffffff801896c000->0xffffff8018994fff dependency: com.apple.iokit.IOReportFamily(47)[77F098F2-012A-32EF-BD19-8A0E7ADF46E9]@0xffffff80189a3000->0xffffff80189a5fff dependency: com.apple.iokit.IOSurface(290.8.1)[3BE6ED95-B932-3F71-9DD5-4563CF4BD0DC]@0xffffff8018a96000->0xffffff8018ab2fff com.apple.driver.AppleIntelKBLGraphics(16.0.5)[493FBA7F-5361-30A7-9A49-57162C8351AD]@0xffffff7fb02a9000->0xffffff7fb0360fff dependency: com.apple.iokit.IOAcceleratorFamily2(442.9)[065DAA9E-DE99-3C6D-A8D6-06BFD26CA1DC]@0xffffff7fb0bb4000->0xffffff7fb0c1efff dependency: com.apple.iokit.IOGraphicsFamily(585.1)[240F08CD-4BC4-3093-8832-0E899EFC14F4]@0xffffff7fb0d35000->0xffffff7fb0d63fff dependency: com.apple.iokit.IOPCIFamily(2.9)[4E85D41F-6AD7-3C24-911C-A8B80B599F86]@0xffffff801896c000->0xffffff8018994fff dependency: com.apple.iokit.IOSurface(290.8.1)[3BE6ED95-B932-3F71-9DD5-4563CF4BD0DC]@0xffffff8018a96000->0xffffff8018ab2fff Process name corresponding to current thread: WindowServer Boot args: chunklist-security-epoch=0 -chunklist-no-rev2-dev chunklist-security-epoch=0 -chunklist-no-rev2-dev Mac OS version: 20G165 Kernel version: Darwin Kernel Version 20.6.0: Mon Aug 30 06:12:21 PDT 2021; root:xnu-7195.141.6~3/RELEASE_X86_64