When going through the SFDC integration steps, you get to the final section, field mapping, and then when you see all the fields that will be mapped you realise there's a lot more than expected, you had given the marketo sync profile access to more fields than intended.
There could be an option to refresh the metadata schema so that the fields not required in Marketo are forgotten about and removed before the finalisation of th setup and commit to the data sync.
There is a reset schema option but this just resets any custom mapping changes you may have made, it doesn't remove fields that are no longer visible to the sync user.
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