Comment 79 for bug 1904293

Similar issue here. I've also tried 5.11.2 but was still seeing significant problems. Adding i915.mitigations=off fixed the problem.

00:02.0 VGA compatible controller: Intel Corporation Xeon E3-1200 v3/4th Gen Core Processor Integrated Graphics Controller (rev 06) (prog-if 00 [VGA controller])
 DeviceName: Onboard IGD
 Subsystem: Dell Device 05a5
 Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx+
 Status: Cap+ 66MHz- UDF- FastB2B+ ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
 Latency: 0
 Interrupt: pin A routed to IRQ 29
 Region 0: Memory at f7800000 (64-bit, non-prefetchable) [size=4M]
 Region 2: Memory at e0000000 (64-bit, prefetchable) [size=256M]
 Region 4: I/O ports at f000 [size=64]
 Expansion ROM at 000c0000 [virtual] [disabled] [size=128K]
 Capabilities: [90] MSI: Enable+ Count=1/1 Maskable- 64bit-
  Address: fee00018 Data: 0000
 Capabilities: [d0] Power Management version 2
  Flags: PMEClk- DSI+ D1- D2- AuxCurrent=0mA PME(D0-,D1-,D2-,D3hot-,D3cold-)
  Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=0 PME-
 Capabilities: [a4] PCI Advanced Features
  AFCap: TP+ FLR+
  AFCtrl: FLR-
  AFStatus: TP-
 Kernel driver in use: i915
 Kernel modules: i915

Installing 5.10.19-200 from updates-testing seems to have fixed the problem for me,

sudo dnf upgrade --enablerepo=updates-testing --advisory=FEDORA-2021-79396b21b2