Ken,
Do you realize that to fly a drone beyond your visual line of sight (without a Governmental Waiver) is illegal in almost every county in the world, and since you are using kilometers verses miles, I am guessing you are in not the US.
Not knowing your visual acuity, I cannot say if you are violation the law in your specific location… The advertisements by DJI as to its signal strength and the relative distances the drone can be flown is only hype to sell their product, not a recommendation to fly to those distances.
On that road that you drone on to get to that location probably had a posted speed limit… You might have driven at twice the posted speed limit and if you did, does not make it OK just because you did…
What other people can do is irrelevant, you should only be concerned with your drone. Have you read the user manual, do you know that your antenna is directional, are you facing your drone, are there trees on the side of the bank of that river where you are flying?
So many unknowns in your story, read the User manual, ensure all your batteries are fully charged and then test it in the open with no obstructions between you and the drone and not other structures that might have a bearing on your signal strength (cell phone towers, power lines, etc…).
Below is the link to all of the downloads offered by DJI for the Mini 4 Pro, including the User Manual.
After you read the Manual, read it again, you will be surprised what you missed the first time and you will be better prepared for that first “scary moment…”
Those YouTubers probably do not care if they lose their drone, just as long as they get the video… One YouTuber wanted to increase their viewership and flew their Mini 3 Pro into a volcano…