I think that high rated FFA games are more difficult for blue and green, my impression is that they finish 4th more often than red and yellow. I don't have any stats on this, but looking at high rated games in the archive, it seems to be a clear trend.
99% loosing with Green

For sure in high rated games BG are doing bad. In my opinion and from experience blue gets the worse of it, I'm actually OK with green. Of course a lot relies in having an opposite who knows what to do and doesn't let you down with BG. Saying 99% is just a joke though, and I don't think this is much of a problem. If BG know what they're doing, they'll get out of the opening just fine. A bigger and real problem is players blaming the meta, or their opposite, or whatever else instead of trying to get better themselves. Review your games people, I'm certain even in games where you got fourth place and thought it was unfair/you didn't get enough support from your opposite, you could've done better and made less mistakes. There are always going to be unfairly bad situations, try to make it as hard as possible for the opponents to really take advantage, try to let them milk out the win.

For sure in high rated games BG are doing bad. In my opinion and from experience blue gets the worse of it, I'm actually OK with green. Of course a lot relies in having an opposite who knows what to do and doesn't let you down with BG. Saying 99% is just a joke though, and I don't think this is much of a problem. If BG know what they're doing, they'll get out of the opening just fine. A bigger and real problem is players blaming the meta, or their opposite, or whatever else instead of trying to get better themselves. Review your games people, I'm certain even in games where you got fourth place and thought it was unfair/you didn't get enough support from your opposite, you could've done better and made less mistakes. There are always going to be unfairly bad situations, try to make it as hard as possible for the opponents to really take advantage, try to let them milk out the win.
Of course, i know that with a good cooperation blue and green can be fine after the first moves. But i talk about the fact that the huge number of games where one of them doesnt do his best on his opposite intentionally.
Fun fact: statistically green does better than all other colours in FFA. Red does worst, and Yellow/Blue are roughly equal
I have felt this in my own games anecdotally but have not dived into the statistics, but I appreciate that you are officially endorsing this.
Due to its rotational sequence, positional value in 4-PC FFA/solo is more along the lines of poker than 2-player chess, in my opinion

I'm unable to share the full data here, but the results speak for themselves:
Above: 1st-place finishes, by colour, from 3.750 FFA Rapid games in 2020 and 2021, where all players' ratings are 2300+.
Below, the same games, but measuring 4th-place finishes:
I hope this helps quell any anxiety you may have about playing as Green.

Hi Grable; interesting, thank you. BUT I'm sure there is another effect that distorts somewhat your stats. You said it's only about 2300+ games; good point. But would it be feasible for you to REMOVE from the equation the games where the 1st checkmate happened within the first 7 (or 10?) moves? I mean, I suspect that because your sample isn't big enough, the effect on the final outcome of a) simple blunders, b) ultra-agressive teams RY openings vs. non-cooperative BG couples or with a very passive B and/or G, is huge. I clearly suspect (because I often play 2300-2400 games) that under 2600 to open badly still happens a lot and it could pollute your stats. I intuitively believe that the stat. advantage for R and Y along with the stat. disadvantage for B and G would disappear or at least attenuate A LOT.

I'm unable to share the full data here, but the results speak for themselves:
Above: 1st-place finishes, by colour, from 3.750 FFA Rapid games in 2020 and 2021, where all players' ratings are 2300+.
Below, the same games, but measuring 4th-place finishes:
I hope this helps quell any anxiety you may have about playing as Green.
I understand that you put the graph to deny what I have said about the 99%, of course it is an exaggeration. On the other hand, I find it quite relevant that in 2300+ the green loses 30%, I am convinced that in 2500+ the difference is much greater. Could you share it please?

Thanks for the stats, @Grable! So as blue/green you have a 50 % higher change to finish 4th than as red/yellow. To me that's serious indicator that you should indeed be worried as blue/green, which correlates well with my playing experience.

@Grable I insist, you could put the same graphics for 2400 or 2500 + I assure you that they will be very different, I dare say that green reaches 40% of the defeats

@Indipendenza:
I can't specifically filter out games that got to a 3-player stage sooner, but I do have the ability to filter by game duration. Here are the same two charts (1st-place by colour, then 4th-place by colour), only looking at games lasting 200 or more plies:
@Manuelgzma:
Filtered to only games where the minimum rating for any player is 2500. There are only 625 games meeting that criteria, so the sample size here might be at issue. Again, 1st-place finishes by colour, followed by 4th-place:
The last chart there got me thinking. I mean 65% probability that B or G finish in 4th among 2500+ players? Wow. - To further explore this trend, I created a graph of BG combined loss probability versus average game rating.
Note: The last bin, 2675 - 2825 average ratings, only contained 91 games, as compared with at least 200 per bin for lower rating categories.

@Grable thanks for ur time. I only wanted to notice the fact that high rated games are extremely conditioned about color, especially green. 67% loses to BG in 2637 rated games is incredible.
Just noticed that last grafic shows how Green has more probability to de 4th than red and yellow together

after 1.r h3 and 1.y i12 green has to defend against mate on the first move)
I think it won't end well)

I don’t know about 2000+, but I still think you can win equally in lower rated games. I feel it also matter on your rating and your opponents rating. When I have played ffa, and I had a high rating and others had lower ratings, i got targeted pretty often.

after 1.r h3 and 1.y i12 green has to defend against mate on the first move)
I think it won't end well)
Green goes l10 or k11 then l8, and what's the problem?

after 1.r h3 and 1.y i12 green has to defend against mate on the first move)
I think it won't end well)
Green goes l10 or k11 then l8, and what's the problem?
it was a fun fact, no more
the problem is that by simply rearranging the king and queen, the "color" problem cannot be solved, the initiative is again in the hands of R/Y. need something more powerful)

Very interesting, thank you Grable.
How come it's not feasible to eliminate the blitzkrieg games (under 10 moves for the first losing player)? Normally the DB stores all the moves, not just the colours of the winners? (I'm sorry to insist but I'm afraid that this factor pollutes totally the outcome, but I may be utterly wrong of course). I wouldn't be surprised if the overrepresentation of G (and BG) losses would be reduced hugely, maybe it won't be 25%, but significantly lower than the current amount.
depends on blue and gren lol