I don't think being dropped from several feet into water would bother a fish in any way, although, being dropped into a keepnet like that could damage their fins or scales if they hit the net below or above the water.
The new trend in rolling a net full of fish into a net head is a bad practice and causes split fins, broken fin rays which don't grow back, knocks off scales which leaves fish open to infections etc etc.
Celebrity anglers like James Robbins seem to promote this and imo they should know better, as many followers of theirs simply copy their antics.
I suppose if fishing a match there is no other option than use keepnets, but it would help if the person/persons involved used some common sense at least.
I can't see any point in using a keepnet if not fishing a match, it's just damaging fish for the sake of it.
My local river has seen an explosion in silver fish numbers to the float fishermens delight. Problem is many of these anglers are obsessed with keeping the fish in nets, and copy the new fad in rolling them into a net head. Lots of youtubers do the same, including a regular one on here. Already i've noticed damaged fish in large numbers. The other day I caught a lot of small'ish roach and virtually evey one has split fins, scales missing etc, it was quite sickening to be honest, I prefer to catch pristein fish.
Now these same anglers will be shouting for the culling of otters etc when the fish numbers start to decline!
Before the mat brigade start shouting at me that I don't use a mat for my barbel, chub pic's....I do if it is necessary. Using a mat for the sake of pleasing others isn't my style. A mat is a health hazzard for fish.
Having kept fish from being a kid (and still do) I do have some idea of how to treat them to keep them in mint fettle

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