The service center telling you to buy a new earbud for a 1.5-year-old device is actually correct for this specific problem, but let me explain why and what your actual options are.
When a single AirPod gets stuck at 1% and refuses to charge despite clean contacts and a reset, it almost always indicates the lithium-ion battery in that earbud has reached deep discharge - a state where the cell voltage has dropped so low that the standard charging circuit cannot revive it on its own. This is different from a dirty contact issue or a software bug.
The image you shared shows the left AirPod at around 1% while the case and right earbud are full, which confirms the charging circuit on the left earbud side is not the problem - the battery cell itself is.
Before giving up on it completely, try this: leave the left AirPod in the case with the case plugged into power continuously for 48 to 72 hours without removing it at all. Some deeply discharged lithium cells can be revived with an extended very low current trickle charge. This does not always work but it costs nothing to try.
If after 72 hours of continuous charging the left AirPod still shows 1%, the battery is not recoverable. Your options at that point are: contact Apple directly (not a third-party service center) to ask about a single earbud replacement cost - Apple does sell individual earbud replacements for the AirPods 4 which is less expensive than buying a full new set. If your AirPods 4 are still within AppleCare+ coverage, the replacement cost may be significantly reduced.
