Can plugin updates be the reason for slowdowns?

There are 11 sites sharing the same theme and one server, the frontend is supported by a caching plugin (clears automatically once a day) and they regularly get slow for short periods of time (like up to 15 minutes a few times a day or more often a page in the admin panel may take a few minutes to open) when me and my colleagues are logged-in in the admin panel. We have a hypothesis that it may be related to plugin updates when one of the sites goes into maintenance mode for example, so the question is, is it possible?

Also I installed a plugin today, then sites were slowed down until I cleared cache. I wonder if it’s related.