solutions suggested by Fabrice

Solution 1:
Create a small pull request that fixes all vale errors. (IMHO, that should be routine anyway)
You can either:
Change to content to make it compliant
Disable the rule on the file
Lower the rule severity in .vale.ini
Pros:
the content had zero errors, keeping it clean from errors is a good idea anyway
some rules are obviously not good for the codebase and should be fixed (the kubernetes rule)
no need to touch tooling
Caveats:
it's a workaround

Solution 2:
Identify precisely what causes the error,
Engage with the Vale community in the Writethedocs slack toolthedocs room to see if others can reproduce.
If necessary, report an issue in Vale repository.