The limit has to do with the database field size (unfortunately the plug-in is serializing everything to one wp-setting). No easy way to get around it.
However, as I’ve asked before in similar threads, is it possible to reconfigure your services to share across forms? As in, register the same endpoint (service) and use something dynamic in the submission (like a hidden field) to route it appropriately? For example, if you need to connect one form to https://pardot.forms/submit?userkey=xyz&formid=123 and another to …submit?userkey=xyz&formid=456, then you might be able to set up the same service to …submit?userkey=xyz and map a hidden field from each form to formid. Also note that any mapped fields that don’t appear in a submission aren’t sent, so you can set up one service with the fields from multiple forms (assuming they share a similar endpoint). Or if you’ve misunderstood how field mapping works and are using unique field IDs rather than reusing labels to send the same data from different forms, you can consolidate services.
I’d be happy to help, and am a little afraid to ask you to share your configuration (from a debug email or migration plugin output) – please scrub sensitive info before sharing.
