In general this board interacts better with BTN's range. We have AK, AQ, KQ type hands more often then BTN does. While both ranges miss a decent amount BTN's range is tighter and will hit more often on boards like this.
So because of that we are cbetting way less or not at all and playing a full check range.
But cbetting is fine. When we do we want a bigger sizing, which is what you did.

+1

std is to xcall, but you can find for ways to improve your result by doing different in case you have any clue about your opponent tendencies.

When BTN then raises it makes little sense. 88, 55 are the only hands I can imagine, doubt people are raising AJ type hands here often. It's way more likely villain has a diamond.
There are several paths to take here. If we would call with range then BTN gets to check turn back and see a free card with his draws. If we raise we likely lose value from a draw heavy range.
Given villain has such a tight value range and is likely overbluffing I would exploit and go for a 3-bet. If we do get called we still have decent equity but I expect a lot of folds.

Strongly disagree with this. No way im 3beting flop with this hand, as played, the question is between fold and call. Even if 55/88 looks like "just a few hands", bear in mind he´s range is very narrow too. So just a few hands, it actually can mean a very big piece of his range.

Just to add to this one of the ways that I'd look to improve your result on the flop is to increase the frequency that you x/r significantly because villains at these stakes often overstab then overfold to the raise.

would you say the underbluffing tendencies of 5 and 10nl players translate to the 25nl pool?

From personal experience playing up to 200nl the underbluffing doesn't stop, it just gets less pronounced. A lot of players either can't hack the variance of very marginal EV plays that involve their entire stack being put at risk or just don't know how to find the bluffs in a given spot. Kind of hard to explain in a quick post because a lot of this is stuff that you just get from bluff catching regs and them always having it but no one really likes the combination of low EV + high variance and you can exploit that by just not paying them off but be careful to look out for those rare players who brought their big boy pants with them.

What DNegs98 said. You've got to have a deeper understanding of ranges aka you have to study on a ton to have optimal bluffing frequencies. Just on this board for example, if you ask 25nl what they bluff raise on this board, they will say give a range of overs + fd , straight flush draws, gutshot combo draws. These aren't even bluffs, as they have a lot of equity and do great vs your continuing range, and shouldn't be raised on this flop anyway. So you got a spot where ranges are so nut/high robust equity heavy combined with an awful raise size, which makes playing your hand super easy.

Oh yeah that's something I forgot actually, strong draws rarely incentivise you to widen your flop calling range that much, particularly given that they get double barrelled at a high frequency and you're just playing a guessing game against a bunch of nutted combos and then some high equity hands. When someone barrels too many draws the nodes that you actually want to start calling off lighter are the turn and river when those draws decrease in equity on bricks so they're actually closer to bluffing them rather than just "investing" in the pot whilst generating fold equity.