Internet disconnections can happen for a variety of reasons, and with the pandemic outbreak disconnections can happen more frequently for reasons outside of either the player’s or Blizzard’s control. You can however track down the source point of a disconnection with careful testing by doing a WinMTR test.
In any case, the starting penalty is only 10 minutes for this reason and as long as you are not deliberately trying to requeue for Competitive, you will unlikely lose too much SR or risk long-term suspensions or bans. Learn more about Blizzard’s penalty policy here: