This sounds like normal water weight fluctuation for someone at your weight.
Typically the first 48 hours of a fasting style calorie reduction sees the fastest weight loss due to water weight loss.
But someone at your weight also has a high RMB (resting metabolic rate) meaning you use more calories for normal bodily functions so anytime you are working on weight loss, you may see larger weight loss numbers than people who weigh considerably less.
Not a Dr or expert, just sharing what I’ve seen and read.
Good luck!!
From what I know it’s absolutely normal at your size range and the trick here is that the more you’re going to lose the slower the weight loss will go - many people feel dissapointed and discouraged that after some time into their wl journey they don’t see such jarring effects as in the beginning despite constant efforts, but it doesn’t mean that your progress itself has slowed down! Quite the opposite! I guess what I’m trying to say that when you go down to, for example, 200lbs, don’t compare how you lose weight then to how you’re losing it now, slower progress is still progress: valid and admirable. I wish you good luck!