Could I have hit my plateau already?

I stared gymming a few months ago. Nothing hectic, mostly cardio. I noticed a difference on the scale as well as cm loss (not a big difference but considering I wasn't spending hours there, nor changed my lifestyle I'm not surprised nor dissatisfied).

Well, I've been weighing myself weekly since starting and I've noticed I'm picking up weight again. Considering I'm barely doing weights I'm concerned. I've also noticed my cm loss has not changed in about a month. I've gained 2kgs.

Could I have hit my plateau already? I mostly walk on the treadmill because I feel I workout the most on that, and then occasionally row. I use the ellipticals a tiny bit sometimes and then I do weights once a week, if even.

My diet isn't that bad actually. I don't eat junk food every day, in fact only once a week maybe. I eat breakfast and maybe lunch, maybe not and then dinner. I snack here and there. Dinner usually consist of a good portion of meat and veggies, and I normally boil everything. We are partial to fries though so we're going to start using the air fryer instead of deep frying them. I drink a fair amount of warm beverages but with no sugar.

Should I start doing more rowing and less walking/ running?