Where is that? I think internet quality varies quite a lot within the EU, urban vs rural, etc so we can'treally generalise. I pay less than 40eur for a 600mbit connection.
While the infrastructure is quite stable where it has been extended, those rural areas ("not prioritized for broadband builds") are also affected by the lockdown, people have to work from home, use the internet all day etc. pp. In those places, the infrastructure reaches its limits pretty quickly all the time. This will cause _serious_ damage to local businesses for no good reason other than ISPs unwillingness to invest there.