I am familiar with at least one current bug with Form 8615. Here is a community page about it:
https://ttlc.intuit.com/community/taxes/discussion/turbotax-2023-bug-with-form-8615-schedule-d-works...
It's possible this is related to your issue. The resulting large jump in tax due when filling out 8615 is consistent with what is seen with this bug, but I'm sure there are many other reasons for a tax jump other than this bug.
