Did they change the filter even ? Quite often these places do a halfass flush and just unhook lines which cause issues and plug lines, filters etc.

You may want to go to a transmission specialty shop with this issue if you're not comfy working on a trans. could be valve related, or just a bad filter.
How many miles on vehicle? Ad how often is trans serviced? And note when you've done a "flush"

__________________
When posting from my phone my typing is horrible.....