@ransomed I've noticed the same thing.
Once a month, I run a program that downloads about 500 stocks, daily adjusted, full sample. Last time (mid December) it took about 30 minutes to complete. Today my program can't even complete due to receiving error messages randomly and receiving no data from the calls. The error messages: "Bad response, error" and "object 'out_xts' not found". If I rerun the call for the stock then the data is received.
I use R and the AlphaVantageClient package to make the calls. And while the error messages could be rooted in the use of the mentioned package, there is definitely a severe slow down.