流程附加＃！ 回调URL

Recently been having server issues on LinkedIn for their OAuth flows. However, from today (26th May) I am receiving a callback with the characters #! appended to the URL.

Sample url I am receiving is:

http://localhost:8081/v0/auth/linkedin/callback?code=AQTkd-3FtQEzWjr-S4hyB_9eCaMrfGY4XpnM3ovj3zehggqkQNBx__G58XPubS98Vej9gkWOPHyALY249AhN7MdgwHb6lJ1ncNlQ40_sSAG94wdk&state=eyJrZXkiOiJkZXZhcHAiLCJ0aGVuIjoiaHR0cDvL2xvY2FsaG9zdDo4MDgyL2xvZ2luLWNhbGxiYWNrP3RoZW49JTI1MkYifQ%3D%3D#!

I can't see what is adding the encode ==#! to the end of the state parameter?

Another integration with MS Graph API works correctly as expected.

Has anyone else seen this with LinkedIn integration recently?