EDIT by @unixfox: The Invidious team is aware of this issue. It appears that it affects all the software using YouTube. Please refrain from commenting if you have nothing new to bring up. Thank you...
Roughly ~1/3 requests yields a loading issue. In case you were wondering why Invidious instances reliability seems to have been in decline very recently.
According to open issue
Additional context
This seems to be a global update, done before 22:23 UTC. (10:23 PM.) From my brief testing, this is present throughout all instances, and regardless of IPv6 address.
Not having a problem with this on my personal instance yet, but I've had to disable DASH because it takes forever to watch anything when it's on these days.