According to the updates listed in the release notes, the current number of updates is not high in r2020a relative to the past 5 years. Keep in mind that the r2020b release is coming soon . According to the FAQ regarding updates, "updates are a set of fixes for an existing installation" whereas an upgrade to a new release often includes new functions, features, and extended functionality of existing features. Some releases contain a large amount of changes and since the number of bugs likely correlates with the number of changes, it's natural that some releases will result in more updates than others.
Since r2015a, there is a median of 4.33 weeks per update. For comparison, the Google Chrome internet browswer is updated every 2-3 weeks (with >10x the employees of Mathworks).
Updates are a good thing. It shows that MathWorks is acting on bug reports and continually improving their product. A new feature could pass the most stringent of tests before it is released but with 4+ million Matlab users worldwide, it's not unlikely that some uncommon interaction may occur that stretches beyond the scope of the those tests and reveals a bug.
But I cannot answer whether there are more bug, a larger rate of bug-detection, or more efficient bug-fixes.
