How do I report this Charitable Contributions BUG???

When using TurboTax Deluxe for 2021 there is a strange bug associated with the Review tab.  After completing both my Federal and State tax returns, including the individual reviews with each of those returns (with No Errors!) and then continuing on to the Review tab (using the step-by-step method), the refund amount decreases with no explanation whatsoever.  By opening the forms view, the issue became obvious... on a tax return for a couple filing jointly, when a standard deduction is beings used in conjunction with the charitable deduction ($300 per filer, $600 total), the tax return enters the proper $600 deduction (which shows with no error). That is mysteriously changed to $300 in the Review tab's 2nd step.  The results are that the refund is decreased and the $300 (which was $600) in the forms view now shows up as an error (invalid amount entered in the field).

 

How in the world am I supposed to report this bug?  And... if it goes unreported, how in the world are the developers supposed to fix the bug???