Looking at most recent 70.0.3538.76 (11021.56.0) stable, we are seeing the 6th highest kernel crash signature is "empty" (note in query this is shown as '').

Top crashes are on Exynos/Rockchip/Skylake platforms. Top outstanding stable signature is "kernel-(HANG)-hung_task: blocked tasks-00000000"

https://crash.corp.google.com/browse?q=product_name%3D%27ChromeOS%27+AND+EXISTS+%28SELECT+1+FROM+UNNEST%28productdata%29+WHERE+Key%3D%27exec_name%27+AND+Value%3D%27kernel%27%29+AND+STRPOS%28product.Version%2C+%2711021.56.0%27%29+%3E+0+AND+expanded_custom_data.ChromeCrashProto.magic_signature_1.name%3D%27%27#-propertyselector,-productname:1000,+stablesignature:50