doing some hand analysis and the hand I was looking at surprised me.

PokerStars - $0.50 NL FAST (6 max) - Holdem - 6 players
Hand converted by PokerTracker 4

BTN: 109.78 BB
SB: 102.26 BB
Hero (BB): 412.18 BB
UTG: 146.84 BB
MP: 102.64 BB
CO: 107.74 BB

SB posts SB 0.5 BB, Hero posts BB 1 BB

Pre Flop: (pot: 1.5 BB) Hero has A J

fold, MP raises to 2.2 BB, fold, fold, fold, Hero calls 1.2 BB

Flop: (4.9 BB, 2 players) T J 2
Hero checks, MP checks

Turn: (4.9 BB, 2 players) 5
Hero bets 6.52 BB, fold

Hero wins 4.66 BB

On the flop, I expected GTO wizard to say HJ should be cbetting this something like 40% since it looks like it connects with BBs range. in reality we should be cbetting this flop >70%! I got looking at other low flop textures and they're all wider than I would expect.

I think I've over-studied btn play with its wide PF range and am transposing that onto EP play. Made me wonder if I'm the only one making this mistake. May be a population leak.
Curious to hear others experience and handhistory's in these spots

I'm confused.

Your subject says population doesn't cbet enough on low flops, but your example flop is JT2

Low/middling. Flops like 268r are similarly bet with a higher frequency than I would expect

A lot of very common leaks in poker come from players missing the nuance of how slightly different textures, positions and previous action affect strategies.
Memorizing sims is not scalable, since there are too many different spots that require different approaches for different reasons.

MP has a massive nut advantage here - tighter range than button range hence lower proportion of 76o type trash. BB is calling down with more Kx and Qx hands - shouldn't have too many junky offsuit Jx and Tx, plus BB has very few sets or two-pair - MP has them all plus all the overpairs. MP can cbet (can use large sizing potentially, I would have thought) here as shouldn't be check-raised often.

actually BB has more sets than HJ as HJ should only be opening 22 with low frequency and BB should be flatting JJ although in game I'm not sure that happens at 50nl. BB has all offsuit JT so significantly more 2p as well. GTO wizard suggests BB checkraising a lot, ~15%, but I think this would be a good exploit to make, getting rid of xr range as BB.

you nailed it with the amount of junk BB has. A lot of easy money picked up from a bet.

100% my leaks come from using heuristics from other spots on the game tree. Probably a flaw of many GTO oriented players. I should be giving more thought to ranges

Yes, this is why usually within the newer or intermediate players, people who play very exploitative styles do a lot better than people who try to stick to GTO.
The formers will be thinking more about both ranges at play and therefor make better adjustments to subtly different situations, and I think, will be better suited for learning and applying GTO down the line.

You are of course correct.