As mentioned already, Hetzner is a very big Hoster in Germany. I am a customer since nearly 15 years now and in all that time they also rised the prices only once for the package I use (and I think it was only recently in 2023 or so where it went from 4,90€ to 5,39€). Also their Storage Box seems to be not only one of the cheapest out there I have seen, but as far as I remember, you do not have to pay for the traffic if you want to restore your data, like it is with other hosters. Also they had a good service, were responsive if I opened a Ticket in the past and I can not remember if I had ever problems with the service I use (Web Hosting package).

is it like a small company that might go out of business in a few years?

Hetzner is one of the largest hosting companies in the world.

They are anything but small. They are probably one of the biggest German hosting companies out there.

I have been using their nextcloud service for several years now and it works great.