The warranty on your Yamaha integrated amp is two years. It is unrealistic to expect Yamaha or the dealer to replace your amp with a new model due to supply chain issues due to parts availability A refurbished amp to replace yours is very reasonable in my opinion. I would jump on that offer.
Long lead times for repairs and repair parts are the reality now. A friend of mine had an issue with his 10 year old Rotel power amp. The local dealer could not get a replacement circuit board. He took his amp to a reputable electronics repair shop. The repair shop can fix the amp, but their lead time is 8 to 10 weeks. I own a high end fly rod and broke it under warranty. The repair shop for that company is swamped and their lead time for the repair is at least 12 weeks.
The reality is that if you own an expensive piece of gear, you need to have a back up or buy another one if you can't live without it.