OP, it is nice that you have come up with this article. I am not a tech guru, but at least I have been in the space for a little while now, and what I know most is that the higher the amount one puts as a transaction fee, the faster the confirmation, but sometimes it seems there is no competition on the mining block rewards (please spare my choice of words), as one can set a little transaction fee and it is quickly confirmed. Another thing I have also discovered is that transactions are quickly confirmed at night, within the time from 11:00 PM to 03:00 AM, but not as quickly as it is during the day, and I believe it is likely the reason being that people do more transactions during the day than at night, or are there any other reasons for it?
Miners prioritized incentives before anything, only few of them mine an empty block in other to get only the block reward but this happen ones or twice in a day and sometimes you hardly see any transaction of such. The more you pay, the quick your transaction get confirmed but it's not a wise thing if you are not in a hurry, just look at the mempool and look at the median fee, you will get the average fee/vbytes to get your transaction confirmed in the next block very quick.
Lastly, I had an experience with the Trust Wallet app when I tried to transfer some Bitcoin to another wallet, but whenever I tried to do such, I always got an error message as UTXO ERROR, even when I increased the fee, the same response I got, and I did this repeatedly, thinking it was a network error. I checked for a wallet update, and the wallet version is up to date. I had to download another wallet and import the private key into the wallet, and I did my transaction without adding any fees. This made me wonder what really happened because I thought that if I increased the fee, the transaction would scale up, but it did not. Can you explain what really happened there?
This is strange, I wouldn't say it's not true but it's not possible because you know why? Trust wallet is an spv wallet and by that, you have to rely on another server to broadcast your transaction, those server will reject any transaction that doesn't comes with a fee. If they accept the transaction without any fee then it will not get included in the next block, in fact the miners will reject the transaction if it's get relay to their nodes.
One of the criteria for your transaction to be accepted by other node is your minrelaytxfee must be greater than 1 but recently, if you look at
mempool.space, there are some mining nodes that are accepting transactions less than a sat per vbytes but minrelaytxfee can't be or equal 0, it's not possible. If you are even able to relay a transaction less than 1 sats, you are likely going to wait a little longer before your transaction get confirmed.