I believe there might be a bug introduced lately to the Android client which causes backoff cycle failed: context cancelled error if the user manually closes "successful SSO login page" popup. If the user just wait for the popup to be closed by the Netbird client, then error does not show up and everything's working as expected. Tested it multiple times on multiple Netbird self-hosted instances (both in v0.60.7 with Authentik as SSO).
There is also another, very similar topic going on in the main Netbird repo. Check it out please: netbirdio/netbird#4883