My RPi4 supports passthrough and if you need TOSLINK then hifiberry (or a Chinese clone) will offer this ability.
I can't believe your TV Boxes stopped working with the latest releases.
Please provide a full debug log.How to post a log (wiki)1. Enable debugging in Settings>System Settings>Logging2. Restart Kodi3. Replicate the problem.Full logs only. No modified logs.Do not post your logs directly into the forum, use pastebin.com and post the link.