Brew update fails due to LibreSSL errors

Currently running osx 10.14.6 with the Supplimental Update. Every once in a while, my system gets into a weird state where brew update fails thusly:

$ brew update
fatal: unable to access 'https://github.com/caskroom/homebrew-cask/': LibreSSL SSL_read: error:06FFF064:digital envelope routines:CRYPTO_internal:bad decrypt, errno 0
fatal: unable to access 'https://github.com/Homebrew/homebrew-cask/': LibreSSL SSL_read: error:06FFF064:digital envelope routines:CRYPTO_internal:bad decrypt, errno 0
fatal: unable to access 'https://github.com/Homebrew/homebrew-core/': LibreSSL SSL_read: error:06FFF064:digital envelope routines:CRYPTO_internal:bad decrypt, errno 0
Error: Fetching /usr/local/Homebrew/Library/Taps/caskroom/homebrew-cask failed!
Fetching /usr/local/Homebrew/Library/Taps/homebrew/homebrew-cask failed!
Fetching /usr/local/Homebrew/Library/Taps/homebrew/homebrew-core failed!

During this time, loading webpages in my browser with devtools open, I see: net::ERR_SSL_PROTOCOL_ERROR 200 (OK)

Usually - but not always - a reboot will make this problem go away for a time.

bad decrypt makes me think that something is being encrypted with openssl and decrypted with libressl in some incompatible way, like using different hashing algorithms. I don’t know enough about homebrew to test that theory, though.

Any ideas on what I could do to figure out what’s going on? Rebooting all the time is not a tenable solution.

brew doctor says:

$ brew doctor
Please note that these warnings are just used to help the Homebrew maintainers
with debugging if you file an issue. If everything you use Homebrew for is
working fine: please don't worry or file an issue; just ignore this. Thanks!

Warning: You have unlinked kegs in your Cellar.
Leaving kegs unlinked can lead to build-trouble and cause brews that depend on
those kegs to fail to run properly once built. Run `brew link` on these:
  docker
  md5sha1sum

brew config is:

$ brew config
HOMEBREW_VERSION: 2.1.10
ORIGIN: https://github.com/Homebrew/brew
HEAD: 925ec737fba1db97d0170c56de982900711cacd3
Last commit: 9 days ago
Core tap ORIGIN: https://github.com/Homebrew/homebrew-core
Core tap HEAD: c7fbfd0d446507eb386a93d27a4defbf33364504
Core tap last commit: 2 days ago
HOMEBREW_PREFIX: /usr/local
CPU: octa-core 64-bit kabylake
Homebrew Ruby: 2.3.7 => /System/Library/Frameworks/Ruby.framework/Versions/2.3/usr/bin/ruby
Clang: 10.0 build 1001
Git: 2.22.0 => /usr/local/bin/git
Curl: 7.54.0 => /usr/bin/curl
Java: 1.8.0_172
macOS: 10.14.6-x86_64
CLT: 10.3.0.0.1.1562985497
Xcode: N/A
CLT headers: 10.3.0.0.1.1562985497

If this is something that is also breaking in the browser it might be something in your connection (proxy/virusscanner/whatever). Either way I don’t think this is something that’s broken in homebrew if you see the results in the browser