Same IP for all visitors

Hi there,
I just experienced within the last two days, two situations where my clients are getting traffic from the same IP address.
So to say all their visits (from hundreds to thousands of different visitors) have all the same IP address whereas all those visitors are coming from all other the world.
-> Is there any known bug about?
Thank you for your help,

@Lukas points me on a right track, my clients may use Matomo with a reverse proxy, which corresponds to the following documentation:
Waiting for feedbacks from my clients in order to confirm if that fix the issue.