Hi smani11 and welcome to the community!
If you have support then I would log a call to get to the bottom of this.
Looking at the trace there appears to be an issue due to “VCSCI Emulation Queue” - can see in the stack that there is mention of getting information from disks? Is this happened during backup windows or random times?
You sad that 'for 3 years there were no problems' but esxi 6.7 was released in 2018 so i guess you meant that after upgrade to 6.7 all was fine. Did you install any vib last days/weeks?
BTW: looks your dump file generated by PSOD is larger than slot size for the core dump partition.
today it crashed again.
The problem occurs during sheduled data backup job. I recognize that by the missing "Success" emails from Veeam.
Not every time, but when it crash, it is during backup.. Veeam says the following .....-->Take a look at the screenshot....
I will delete and restore the VM. Hope it fix the problem.-Simon