I did a quickie look at Coinbase fees and it appears to be 0.6% on each side... so if you have one trade that involves both selling and buying back (or buying and then selling) it would add up to 1.2% for both ends of the trade.. which is not outrageous since there are two trades involved.
https://help.coinbase.com/en/exchange/trading-and-funding/exchange-feesHahaha..that's OLD fees, which were OK.
Now, when as they increased fees, you can see them either with an AI search or ONLY when you login to this website:
https://help.coinbase.com/en/coinbase/trading-and-funding/advanced-trade/advanced-trade-feesAI overview:
Coinbase Advanced fees are based on a maker-taker model, determined by your 30-day trading volume and asset balance. Fees decrease as volume increases, starting around 0.60% maker / 1.20% taker for low volumes and potentially reaching 0.00% maker / 0.05% taker for high-volume traders. You can access Advanced Trade through a standard Coinbase account at no extra charge.
EDIT: see better explanation from @d_eddie Taker-fee when you sell
...and by the low volume they mean $10K.