After some trial and error, I found that the Lenovo IdeaPad Slim 7i Pro had two issues running Ubuntu and its derivatives.
First, the keyboard doesn't work right away at the login screen because the virtual i8042 keyboard controller implemented in the BIOS is not properly delivering interrupts when the keyboard sends three bytes (fa ab 83) in a too quick succession. Adding i8042.dumbkbd kernel parameter fixes the issue.
Second, Panel Self Refresh (PSR), a power saving feature used by Intel iGPUs is known to cause flickering. A temporary solution is to disable this feature using the kernel parameter i915.enable_psr=0.
Third, Some NVMe devices may exhibit issues related to power saving (APST). This happens on ADATA SX6000LNP 1TB. As a workaround, add the kernel parameter nvme_core.default_ps_max_latency_us=0 to completely disable APST.
So, we need to add i8042.dumbkbd, i915.enable_psr=0 and nvme_core.default_ps_max_latency_us=0 kernel boot parameters in order to run Ubuntu properly. Follow