Not necessarily, no. It's downvoted because it's one low-evidence anecdote amidst comments from people who've been using it daily (two years, here). That doesn't mean it didn't happen, but without supporting evidence it's difficult to find relevance in a single poor call.

Some basic evidentiary questions for you to consider, that would help distinguish between "someone's Internet was broken" (more likely) and "Zoom is defective" (less likely), for example:

1) Was only one participant experiencing issues, or were all participants blurry? Did Zoom warn you that of connection instability? Did Zoom show yellow or red connection status bars for the affected participant(s)?

2) Does your (or their) Internet connection show instability such as high latency (Bufferbloat) when performing a speed test capable of measuring and reporting latency-under-load fluctuations? https://dslreports.com/speedtest

3) Did the sound quality issue involving one or more participants who were not using in-ear or over-ear headphones?

4) Was the sound quality issue reproducible in a followup call for testing? Was it reproducible using "call in by phone" audio rather than "internet" audio for testing?

EDIT:

5) If you stop sharing your video, does the problem improve? If you activate screen sharing, does the problem worsen?