The consent mode issue was fixed in 2.0.5, so the latest patch stopped working. Original patch by @emanaton works fine.
Patch #2 also solved the issue for us on 10.2.3.
Had the same issue as described. Changing the count to a lower value made the error go away. Save a new campaign does still take a long time, though we manage this by raising the timeout in the module settings.
Created an issue fork and changed the count to 10. Created a merge request: https://git.drupalcode.org/project/mailchimp/-/merge_requests/57.
pieter-e1 → made their first commit to this issue’s fork.
Updated the first patch to add separating dots in the date of birth (xx.xx.xx-xxx.xx).
Fixed #6, it was based on a commit that has not been merged yet.
Seeing as how there haven't been any reactions to #5 ✨ Allow permanent redirect instead of temp redirect Needs review , I have updated the patch for version 8.x-1.0-beta12, on D9.5.2 without any functional changes.