Just checked coinbase now and it is working fine. The outage and disruption was not because of Robin Hood but because of Elon Musk status changed to "Bitcoin BTC" which caused the big pump in the market and as usual coinbase unable to handle lot of traffic.
Coinbase Pro and Kraken have been having problems with their server since noon today. without giving any previous notice They are showing service maintenance. Nowadays if you open Kraken and see that they are in maintenance then it is confirmed that the price is either at the top or at the bottom.
The main reason I think is this one
why more of the exchange experiencing technical PRoblem
https://cryptobriefing.com/crypto-exchanges-report-technical-issues-following-secs-warning/ . and obviously if its US base exchange they are following US SEc market warning for being volatile of the market and risk of many people to lost their capital if they enter in it.