Current working theory is that coffee lake refresh is not supported by FreeBSD 12.1.
To confirm, you could run lspci -qnn , that should get you the PCI ID of your iGPU.
# lspci -qnn
00:00.0 Host bridge [0600]: Intel Corporation 8th Gen Core Processor Host Bridge/DRAM Registers [8086:3ec2] (rev 0a)
00:01.0 PCI bridge [0604]: Intel Corporation Xeon E3-1200 v5/E3-1500 v5/6th Gen Core Processor PCIe Controller (x16) [8086:1901] (rev 0a)
00:02.0 VGA compatible controller [0300]: Intel Corporation UHD Graphics 630 (Desktop 9 Series) [8086:3e98]
00:12.0 Signal processing controller [1180]: Intel Corporation Cannon Lake PCH Thermal Controller [8086:a379] (rev 10)
00:14.0 USB controller [0c03]: Intel Corporation Cannon Lake PCH USB 3.1 xHCI Host Controller [8086:a36d] (rev 10)
00:14.2 RAM memory [0500]: Intel Corporation Cannon Lake PCH Shared SRAM [8086:a36f] (rev 10)
00:16.0 Communication controller [0780]: Intel Corporation Cannon Lake PCH HECI Controller [8086:a360] (rev 10)
00:17.0 SATA controller [0106]: Intel Corporation Cannon Lake PCH SATA AHCI Controller [8086:a352] (rev 10)
00:1c.0 PCI bridge [0604]: Intel Corporation Cannon Lake PCH PCI Express Root Port #6 [8086:a33d] (rev f0)
00:1d.0 PCI bridge [0604]: Intel Corporation Cannon Lake PCH PCI Express Root Port #9 [8086:a330] (rev f0)
00:1f.0 ISA bridge [0601]: Intel Corporation Z390 Chipset LPC/eSPI Controller [8086:a305] (rev 10)
00:1f.4 SMBus [0c05]: Intel Corporation Cannon Lake PCH SMBus Controller [8086:a323] (rev 10)
00:1f.5 Serial bus controller [0c80]: Intel Corporation Cannon Lake PCH SPI Controller [8086:a324] (rev 10)
00:1f.6 Ethernet controller [0200]: Intel Corporation Ethernet Connection (7) I219-V [8086:15bc] (rev 10)
01:00.0 Serial Attached SCSI controller [0107]: Broadcom / LSI SAS2008 PCI-Express Fusion-MPT SAS-2 [Falcon] [1000:0072] (rev 03)
02:00.0 Ethernet controller [0200]: Intel Corporation I211 Gigabit Network Connection [8086:1539] (rev 03)
03:00.0 Non-Volatile memory controller [0108]: Intel Corporation SSD Pro 7600p/760p/E 6100p Series [8086:f1a6] (rev 03)