Problem seems to be specific to most recent companion app update. Using previous version resolves this issue. You can find previous versions here: https://www.apkmirror.com/apk/bungie-inc/destiny-2/
You will need to uninstall current version before installing previous versions. I am using version from January 9th and am able to join fire teams. Good Luck!
I can confirm the workaround is working and is possible to join and create fireteams as @Orinthium mention.
Use this link to download the APK directly: https://www.apkmirror.com/apk/bungie-inc/destiny-2/destiny-2-14-9-0-release/destiny-2-companion-14-9-0-build-2508-android-apk-download/