You fold to c-bets too often. Here is the number that proves it.

A continuation bet costs your opponent about two thirds of the pot. If you fold more than 55% of the time when they make one, betting any two cards at you is instantly profitable. They do not need a hand. They need a bet.

Most losing regs fold to flop c-bets somewhere between 60% and 70%. The player betting into them does not know your cards. They know your frequency. And frequencies leak through in a few hundred hands to anyone paying attention, including the software many online players run.

Why it happens

You called preflop with a hand that plays nicely when it hits: suited connectors, small pairs, broadway cards. The flop misses you, which happens about two times in three. You check, they bet, you fold. Each individual fold feels fine. The pattern is the leak.

The mistake is treating "did I hit the flop" as the whole question. The real questions are: how does this board hit their range, how does it hit mine, and what does my hand do on later streets?

The fix, concretely

Keep your pairs. Second pair and third pair are bluff-catchers by design. Against a normal c-bet frequency, folding second pair on the flop to one bet is burning equity. Call once and re-evaluate.

Keep your backdoors. A gutshot, two overcards, a backdoor flush draw: these hands continue profitably against a small bet, because when you improve you win big pots and when you raise the turn you take the pot away.

Fold your true air. The goal is not to defend everything. It is to stop folding the middle of your range. If you have no pair, no draw, and no backdoors, folding is correct and you should do it without regret.

Attack small bets. A one-third pot c-bet needs to work 25% of the time to break even. When someone bets that small into you on a board that favors your range, raising with your good hands and your best draws punishes them immediately.

How to know if this is your leak

Count your last 50 faced c-bets. If you folded 30 or more of them, this is costing you real money at every stake. The number moves slowly, so drill the spot deliberately: face flop bets holding marginal pairs and draws, and practice the call.