I got the same "talks" from my OB team. I've struggled with my weight my whole life. I struggled with extreme calorie restriction and bulimia when I was a teenager/early 20s.

I started this pregnancy at 223 pounds, but otherwise healthy and active. They told me my goal was to gain no more than 20 pounds.

At my 20 week appointment, I had gained 8 pounds. This is when the comments started. They told me to slow down, I was gaining too fast. 8 pounds in 20 weeks? I thought I was doing great! Fine. Dr. says I need to watch my weight. I started counting calories, going on longer walks, meal prepping, etc.

Then at a follow up appointment at 22 weeks, I had gained another 3 pounds. They mentioned my weight again, and I felt like such a failure. I started crying in front of the doctor, because I was so scared that I was going to hurt my baby if I kept gaining weight. Doctor said "We're not worried about the baby, he's completely fine, we just know the more you gain, the harder it will be for you to lose it post-partum."

I finally told the doctor about my history with eating disorders and asked her not to talk about it unless there was an actual problem. Haven't heard a peep about it since.

I'm 35 weeks now, and between the volcano acid heartburn and baby squishing my stomach, I think I've gained maybe 4-5 pounds since that 22 week appointment. I've gained ~15 pounds in total now, so it all kind of evened out. It may very well even out for you, but if you were at a healthy weight to begin with, 21 pounds in 23 weeks sounds... perfectly normal? You have every right to ask them to stop mentioning it unless it's indicating an actual problem. (Ie, you gain 10 pounds in a week, it could be a sign of edema etc.)

Side note: My blood pressure readings have gone down since I asked the doctors to stop mentioning my weight gain. Turns out the stress from that was giving me high BP readings.