Your situation is not unlike that of a lot of sellers. The pandemic drove and explosion in ecommerce and eBay is no longer the only game in town. I diversified a long time ago across multiple platforms and venues and eBay which used to account for about 90% of my sales by volume now only accounts for about 20%. There are a LOT of specialty online sites that cater to a targeted buyer market and audience. There are several targeted at the quilter market.
Shipping is also becoming a major factor especially for lower priced items where the shipping cost drives the total cost of the item out of the competitive market range. I seldom list lower dollar items these days but tend to bundle items into lots and the shipping cost for a lot of items is often the same or a few cents more than what it would have cost the buyer to ship a single item.
Good advice on using "sell similar" I do that on items that are 4-5 months old. Others suggestions about sending offers is a good one and hope that works out well for you. Like you I have lost my TRS a few times due to low total volume sales but it really has not harmed my sales that much and I eventually get the TRS back.
The best way to find ways to improve your sales is to experiment with different approaches and options. Consider diversifying to other platforms and venues and possibly your product line. Above all AVOID the use of promoted listings it is a death spiral race to the bottom. There is no way to prove the use of PL improves sales and the only one it benefits for sure is eBay.
