Should I call facing this turn jam in a 4bet pot?

A5s is a mandatory bluff given OOP's 4bet range. It doesn't matter that it flopped a pair; it's still bottom of range (after AK).

I'm definitely not assuming that V is going to be "balanced" in his actions. I'm looking at what balanced ranges look like, but as I made clear in the latter section of my post, the vast majority of live low stakes players will become imbalanced in 4bet pots due to inexperience. In other words, they will be either value-heavy or bluff-heavy (generally the former, although to a lesser extent than in 3bet pots, because the lower SPR in 4bet pots makes the postflop play somewhat easier).

If he is balanced then there are a few ways he can approach the hand but when OOP as the aggressor in a 4bet pot on a Q-high board, he should be checking a lot (because a lot of his range is AK). If he's going to cbet then in general I imagine the optimal way for him to play will be for him to play a two-street game. Regardless of how he chooses to proceed, we simply have to respond in a balanced and hopefully unexploitable way. If you believe that "in a 4-bet pot, after we call his flop c-bet, most V's are NOT going to have any bluffs when they jam turn. Most V's are not going to be balanced here" then the play becomes pretty straightforward because we know villain always has it when he bets.

"If we believe this V is capable of being balanced, then we have to count up all his bluff combos and value combos, and see if we're getting the right price to call".

If he is correctly balanced on the turn, then it should be a bluff 385/1210 x100 = 31.8% of the time. I would need 15 outs to make a profitable call. Although this hand is kind of unusual in the fact that a lot of his bluffing range is AK, which I'm freerolling due to the flush draw. So if I run into his value range, I have a profitable call, and if I run into his bluffing range, I have a freeroll - but it's going to be a chop 64% of the time, and that kind of messes with the equities a bit.

"If WE want to be balanced, we need some bluffs, and AKdd is the best bluff possible on the flop, whether V c-bets with any bluffs or not. It really doesn't matter if he doesn't. Like, what are our value hands if we jam flop, other than AA, KK, and QQ, if we're saying AQ is a bluff? (If you're not saying AQ is a bluff, I'm saying it, because what is AQ beating that will call a jam?)"

Sure, AKdd is a fine semi-bluff facing the flop bet, but in theory we also need some airballs in there because AKdd has a boatload of equity (it's at 47% vs KK, for example) and is therefore not strictly a bluff in terms of equity. When we jam we will be giving villain the same price as what he gave us in the hand as played on the turn (31.8%). If we're gonna jam the flop with whatever AA and KK we slowplayed preflop (let's say four combos for the sake of argument) then we're gonna need two airballs for balance. Similarly to villain I believe we should use A5 as bluffs as well as the very small amount of suited connectors that we have in our range. That said, when I checked this with a solver, hero had no raises vs the flop bet:

and this is also one way that submersible suggested playing.

Calling the 4bet and 5bet jamming pre (assuming villain 4bets a reasonable range) are usually similar in EV and therefore hero can simply mix between the two. However, as mentioned earlier in the thread, I don't buy that most low stakes players are 4betting as wide as they should, and therefore my default adjustment is to be careful with 5bet ripping unless villain has shown themselves to have a willingness to 4bet a tighter range than what can be expected vs most low stakes players (KK+ and AK if you're lucky, lol).

I ran a solve to see what bluffs it used for villain on the turn after the flop went cbet 25% pot and call (as played in the hand). This is what it gave:

As expected, many combos of AK (although not necessarily those with a diamond; I guess villain wants hero to have the ace of diamonds in his hand and therefore be more likely to fold to the turn jam, not getting the right price with the flush draw) and the two combos of A5s. It's interesting that it prefers to use A5s rather than ATs; I'm not sure why that's the case. AQs is mixing between value betting and check-raising, and QQ is slow-playing (and will check-jam if faced with a stab, like all of villain's value range from AQ+.