I have taken a dozen CompTIA exams online using OnVue since the pandemic started. I've taken OnVue for other certification exams as well.
I've never had any significant problems. One time, a proctor claimed to have lost my webcam feed. The proctor rebooted my exam and everything went fine after that. Other than that, all of my OnVue exams have run flawlessly.
The vast majority of complaints I've seen were from people who didn't follow or read the rules. If someone gets out of the webcam view, that's a violation. If they lip-read each question, that's a violation. I've heard cases of people not being allowed to test because they were wearing headphones. Headphones are not allowed. You must have working speakers. I saw a case of another tester who thought they could take the exam on a tablet, which they could not. In almost all cases, testers had their exams canceled because they didn't follow the rules. That's on them, not Pearson Vue.
My nearest test center is ten miles away in Tampa Bay traffic. A better option is to walk into my home office, which I use to teach remote classes, and sign in to test remotely using OnVue. All I have to do before signing into the exam is remove the secondary monitor and clean off my desktop surface. Easy peasy.
ISC2 does not allow online testing. I had to drive to a test center more than 20 miles away to take my CISSP. It took me an hour in traffic on a Saturday morning to arrive. After I passed, it took another hour to get home.
If online testing is an option, I will choose it every time. I will only go to a testing center if online testing is not an option.