With this specific representation:
If your transaction fee is right below the white mark
and a block is found right after they received your transaction, it is very likely that it will be included.
However, if you broadcast your transactions with a fee just below the white line, and the next block is found in a minute or later, the chances are high that there will be more transactions broadcasted with a higher fee than yours. This will lead to your transaction not being included.
Now if I set a fee that is just outside the dashed white line does that mean my transaction will get priority and put on the next block? or can it be pushed all the way to the end of the mempool cue if it was a very low fee?
This fully depends on:
- how many transactions will be broadcasted until the next block is found
- how high their fee is
If the next block is found within a second, your transaction most likely will be included.
If there will be more than 1 MB of transactions with a higher fee, your transaction will not be included.
What wallet are you using ?