Am I the one doing it wrong? (Handicap sandbagging?)

I’ve been playing in a men’s league for a couple years now. It’s teams in match play format. I’ve noticed a lot of people I play against will concede a hole and then write down the number of strokes where they are laying. Example would be my ball is 5’ from the hole laying three for a par putt. Their ball is off the edge of the green laying 4. They say “yours is good. Put me down for a five”. Essentially simulating that they would have holed the chip.

In that scenario I would have played my ball to a reasonable spot on the green then conceded and had a number closer to reality to put on the score card. Or if we’re in danger of playing slow I would have said six, simulating a chip and one-putt.

I see a lot of people playing with 9-hole handicaps that are probably 2-3 strokes lower than they should be. Or Am I sandbagging my handicap and I’m the one doing it wrong?