Stack Overflow RSS Feeds returning 403s

The tag-based RSS feeds for stackoverflow.com are returning 403s today. For example, this Kotlin feed 403s:

https://stackoverflow.com/feeds/tag?tagnames=kotlin&sort=newest

as you can see at the W3 validator:

https://validator.w3.org/feed/check.cgi?url=https%3A%2F%2Fstackoverflow.com%2Ffeeds%2Ftag%3Ftagnames%3Dkotlin%26sort%3Dnewest

The meta.stackexchange.com feeds appear to be working fine as are the cooking.stackexchange.com tag feeds. I also did a quick check for serverfault.com and that seems okay.

Originally noted in the wrong place where it was closed rather than moved:

Stack Overflow RSS Feeds returning 403s