it's strange staking in my wallet. I've got 3500 coins, but all time I see increasing days for staking. for example 3 days ago I had 4 days, but now I see 5 days for staking.. it's look like I never take my profit


it's a bug? or my mistake in wallet? what is wrong?

The problem is that others are buying or mining coins and adding to their wallets, thus making your percentage of staking coins smaller in relation to the entire network. So, unless you buy more coins and add to your wallet, your staking days will only grow before they stake rewards.