Good advice!Taking out the rock and livestock, replacing sand and new salt water, then putting livestock back is not going to fix the issue.
If it was me I would add more fish and increase the bio load. Don’t dose any “reef safe” medication or magical elixirs. If you have Dino’s from water changes don’t do any water changes. Wait for the Dino’s to get out completed. There are threads on how to beat Dino’s and it doesn’t appear you nitrate and phosphate are bottomed out. An ultraviolet sterilizer may be something to consider, permanently or temporarily.
If it has been 22 months, bacteria should not be an issue. All the coral that you added would have bacteria on it that would help seed the tank. That’s just me, I am a dry rock fan.
Keep it simple , go slow, nothing good happens overnight. Listen to the folks in this thread, your tank is beautiful.
Many people will say do this or do that. Stability is the key to success