What does regression mean here? [closed]

The word "regression" has a specific meaning in programming, which can be found in Wiktionary:

(programming) The reappearance of a bug in a piece of software that had previously been fixed.

Thus, "regression" in the text provided seems to imply that there had been bugs previous to this.

In this case, regression is referring to a software bug that was fixed earlier, but has reappeared due to changes to the software or the modules it depends on.

In software development, it is common to do regression testing. This is a process which is done either manually, by a quality assurance (QA) team, or automatically using a set of unit tests. It is done to ensure that operations that were working before changes were made to the software still work after the changes were made. If the changes cause things to break, those breakages are known as regressions.