Apologies if this isn't the right sub to ask this in, but I was thinking it likely would be.
Recently I got a pair of Soundpeats Air4 Pros for just $29. I'm finding them to be pretty amazing for what their normal price is ($80~) let alone what I got them for, but that's not what this post is about - I just wanted to throw them some love.
Anyway, I am very sensitive to audio latency in games/videos and these buds support aptx adaptive and also have a game mode that can be turned on and off, which reduces latency by an amount I am unsure of. When using my phone (Galaxy S10), I can see in developer settings that it defaults to regular aptx as I believe that is the best codec my phone can support besides aptx HD, which is unselectable (I guess because the buds only support adaptive and not HD? Not an issue I'm concerned about). SBC is the only other option I have. Both options have terrible latency and turning game mode on with the buds cuts it down by maybe 25-50%, but that's not nearly enough and is still really bad for games or videos. aptx only seems to be very slightly better than SBC.
Then I have an ipad, which is several years old now. I want to say 6th gen maybe? I am unsure what codec it uses, unfortunately. However, I get pretty noticeable improvement here for whatever reason. Without game mode, latency is probably only a little worse than with game mode on my S10. With game mode on the ipad, the latency becomes only slightly noticeable to the point that I can say it's actually not that bad. For the bit of gaming on my ipad, I really don't mind it. I assume latency is so much better here than my S10 because of whatever codec is being used perhaps, but I don't know.
Up next is my PS5, which I just got a bluetooth adapter for that supports all aptx codecs and SBC. What's nice is that with this adapter, I really don't know that I can tell there's latency there at all, so that's great! However, I'm really confused because I don't notice almost any difference between codecs here. aptx LL and HD are unsupported for my buds, so it defaults to adaptive, which seems to work very well except weirdly game mode doesn't seem to do anything with adaptive on. It almost doesn't need to, though, luckily. BUT, if I set the codec to SBC or normal aptx and turn game mode on, the latency becomes just as good, if not BETTER, than adaptive. If I don't turn game mode on, the latency feels as bad as it did on my S10 or so.
Then I've got my Switch with it's normal SBC bluetooth. Connecting my buds without game mode is probably the worst latency out of any device here... but then it becomes virtually unnoticeable once I turn game mode on.
I'm really confused about this... why would the game mode function on my buds be pretty much fully fixing SBC/aptx latency on my PS5 and Switch, but not on my S10 or ipad? And how could it be improving the latency so well on my PS5 and Switch to the point that it seems like the better option compared to aptx adaptive?
Are there probably just way too many variables at hand and a straight answer can't really be given?
Latency is a combination of hard and software.
Robert Triggs did some measurements: https://www.soundguys.com/android-bluetooth-latency-22732/
On older smartphone latency runs as high as 500 ms, on newer models it dropped to 40 ms and lower.
Indeed it take two to tango. Your phone might have APTX-LL (low latency), if your buds don't have it, it cannot be used.
True gaming headsets often come with their own dongle. They use their own protocol to circumnavigate the latency of Bluetooth. Likewise the gear used in live sound https://www.shure.com/en-GB/performance-production/louder/digital-wireless-latency-explained
Bit more detail about Bluetooth: https://www.thewelltemperedcomputer.com/HW/Bluetooth.htm