OS and driver changes could make a difference
I have not upgraded to OBS v28 yet, but OBS in itself, I wouldn't suspect of being the cause. But depending on other plugins, and your OBS setup, sure something may have changed, or a plugin may be using more CPU than it used to and now your system is overloaded? or misbehaving. or, with OS and application updates, something else may now be running in the background that wasn't before (or running differently, like antivirus and other security software), and that is causing the problem.
For example, you have have done an operating system update, and that isn't playing nice with an audio driver you have?? maybe? maybe not?
See pinned post in this forum, or link in my .sig) about posting your OBS log (which won't tell us about your OS and its workload)