Good Morning,
Your gardener probably pruned off all the flower buds because Bigleaf Hydrangeas primarily bloom on last year’s growth, or “old wood.” For this reason, bigleaf Hydrangeas should never be pruned in late summer or fall. Pruning last year’s growth effectively removes the next season’s flower buds. 
How do I protect my ENDLESS SUMMER Hydrangea over the winter? | Extension (unh.edu)
Hydrangea.pub (wisc.edu)

You may clip off flower heads anytime. Just clip above a pair of side buds so that stem will continue to produce leaves and flowers if it isn’t killed over winter. Some gardeners like to dry the flowers and use them in dried arrangements, or decorate in fall and winter, over the holidays. Hydrangea may bloom on old wood if you give it winter protection (see above articles).

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Thank you very much for the very helpful information.