ERA5 valid_time counts in seconds

When displaying hourly data from ERA5 starting from 1940, CDO misinterprets the time axis (valid_time) as starting in 1970 and counts the time in seconds instead of hours. I didn’t have this issue with the previous data store.
How can I fix this issue?
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Same issue with ncview for the monthly data, which does not decode the valid_time correctly. Why use valid_time instead of time as before?