I think the number of players not playing real EQ (and/or spending less krono) because of THJ is non-zero, but I have no idea how DBG could possibly hope to prove any amount of lost players, especially if they're forced to give hard numbers for prior TLP releases and the like. Their prior bomb TLP releases should reflect that quality of TLP matters and fluctuates.
beyond anecdotal evidence I doubt very much that they've lost any money at all to THJ, certainly not in any amount that could be proven. In fact it would be easier to argue the opposite, that bringing in tens of thousands of former eq players and giving them an accessible, solo version of the game, may have reignited nostalgia enough for a few of them to actually resub to EQ.
Daybreak had between 10-20k subscriptions as of that 2023 video (was hard to tell on the bar graph) but lets, for shits and giggles, say it was 20k subs 2 years ago, and i'd wager they attrition out 10% per year, more on years with shit TLPs like this years, but lets say 20% for the 2 years. so lets say it's now 16k subscriptions. with the average player maintaining between 3 and 6 subscriptions, lets say 4, you really are only dealing with about 4k players remaining. EQ has zero new players this is a terminally deteriorating player base, and it appeals to less and less people each year as nostalgia wears thin and the absolute shit mismanagement upsets players. also, their players are starting to age out of gaming and/or life itself.
THJ realized that there was actually a million former EQ players who got older, had families, have jobs, etc, most if not all of which, swapped to WoW when it released (or some other MMO) and realized that their time was too valuable to not be able to play the game in any meaningful fashion unless grouped, that soloing was the way of the future and forced grouping is a young man's game.
THJ has 20k+ and growing playerbase pulling from former eq players who can't or won't play Daybreaks EQ. which is why thinking "1/4 of THJs players came from TLPs" is ridiculous. 1/4 of THJs players is more players than Daybreak even has, if that were the case then they would of shut down the servers cus they had 0 players remaining.
There is little to no cross over between the 2 player bases for the same reason that daybreak would never offer a server like this, and it's the same reason that they don't enforce any truebox rules.
Daybreak is milking the handful of subscribers they have remaining for 100+ a month in subscription fees plus whatever in krono because EQ is fundamentally a group required game, but the playerbase has aged to the point that that is no longer a viable playstyle model, which forces them to multibox and maintain multiple subs to play.
They still exist by promising true box alternate ruleset TLPs to bring in the old school nostalgia fans but cater exclusively to the loner 6 boxer farming content and selling shit for krono.