Hey, I totally understand the worry, 1kg per week does sound on the heavier side, though it's good your BP and other markers are looking fine. From what I've heard around, most mums gain about 3/4 to 1 pound per week in the third trimester (so roughly 0.3 to 0.5kg), and it often tapers off in the final month or so; overall for the whole pregnancy, people tend to land somewhere between 10 to 14kg if they started at a normal weight. That said, every body is genuinely different, some of it can be water retention, baby size, or how you're carrying, so it's really worth having a chat with your gynaecologist or midwife about whether this pace is something to adjust or if there's a particular reason it's happening for you. They'll know your full picture and can give you the most reassuring or actionable answer.
I'd say 1kg per week is on the higher side, especially if it's sudden, so it's worth flagging with your gynae or PD just to rule out water retention or anything else going on. Normal third trimester gain is usually around 0.3 to 0.5kg per week, though everyone's different depending on their starting weight and how much they gained before. Since your BP and other signs look good, it's probably nothing serious, but better to check in with your doctor rather than worry yourself, especially since you've noticed the change.
hope this article helps https://sg.theasianparent.com/how-much-pregnancy-weight-should-you-gain