GitHub public code search limited?

Not sure if folks here browse github without logging in, but if you try to do a code search it seems like they might be experimenting with limiting public code search?

Example:

https://github.com/search?l=Dockerfile&q=from+python&type=Code

Response:

"We could not perform this search

Must include at least one user, organization, or repository"

Maybe this is only an intermittent thing as they rebuild their search indexes? Maybe it's a new 'feature' being rolled out?

This also seems to come and go for me as a logged in user.