The new kernel 5.10.xxx does not work for me either. I am using the Budgie desktop.
After reading this discussion I found only one way to get to the desktop with the kernel parameter amdgpu.dc=0. But the desktop remains usable only for about 10 seconds and then crashes with artifacts.
For me only the kernel 5.6.19.xxx is usable.
I will wait until the problems are fixed until I update my main machine with Intel CPU and AMD GPU.
My test machine is an Ideapad from Lenovo with full AMD hardware:
~ $ lspci
00:00.0 Host bridge: Advanced Micro Devices, Inc. [AMD] Family 15h (Models 60h-6fh) Processor Root Complex
00:00.2 IOMMU: Advanced Micro Devices, Inc. [AMD] Family 15h (Models 60h-6fh) I/O Memory Management Unit
00:01.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Stoney [Radeon R2/R3/R4/R5 Graphics] (rev eb)
00:01.1 Audio device: Advanced Micro Devices, Inc. [AMD/ATI] Device 15b3
00:02.0 Host bridge: Advanced Micro Devices, Inc. [AMD] Family 15h (Models 60h-6fh) Host Bridge
00:02.4 PCI bridge: Advanced Micro Devices, Inc. [AMD] Family 15h (Models 60h-6fh) Processor Root Port
00:02.5 PCI bridge: Advanced Micro Devices, Inc. [AMD] Family 15h (Models 60h-6fh) Processor Root Port
00:03.0 Host bridge: Advanced Micro Devices, Inc. [AMD] Family 15h (Models 60h-6fh) Host Bridge
00:08.0 Encryption controller: Advanced Micro Devices, Inc. [AMD] Carrizo Platform Security Processor
00:09.0 Host bridge: Advanced Micro Devices, Inc. [AMD] Carrizo Audio Dummy Host Bridge
00:09.2 Audio device: Advanced Micro Devices, Inc. [AMD] Family 15h (Models 60h-6fh) Audio Controller
00:10.0 USB controller: Advanced Micro Devices, Inc. [AMD] FCH USB XHCI Controller (rev 20)
00:11.0 SATA controller: Advanced Micro Devices, Inc. [AMD] FCH SATA Controller [AHCI mode] (rev 4b)
00:12.0 USB controller: Advanced Micro Devices, Inc. [AMD] FCH USB EHCI Controller (rev 49)
00:14.0 SMBus: Advanced Micro Devices, Inc. [AMD] FCH SMBus Controller (rev 4b)
00:14.3 ISA bridge: Advanced Micro Devices, Inc. [AMD] FCH LPC Bridge (rev 11)
00:18.0 Host bridge: Advanced Micro Devices, Inc. [AMD] Stoney HT Configuration
00:18.1 Host bridge: Advanced Micro Devices, Inc. [AMD] Stoney Address Maps
00:18.2 Host bridge: Advanced Micro Devices, Inc. [AMD] Stoney DRAM Configuration
00:18.3 Host bridge: Advanced Micro Devices, Inc. [AMD] Stoney Miscellaneous Configuration
00:18.4 Host bridge: Advanced Micro Devices, Inc. [AMD] Stoney PM Configuration
00:18.5 Host bridge: Advanced Micro Devices, Inc. [AMD] Stoney NB Performance Monitor
01:00.0 SD Host controller: O2 Micro, Inc. Device 8620 (rev 01)
02:00.0 Network controller: Qualcomm Atheros QCA9377 802.11ac Wireless Network Adapter (rev 31)
I don't like the discussion about LightDM or Gdm as the problem is deeper.