Exrreme weight fluctuation of 42 kgs in 2 years, is there a problem with me?

I'm 37m and have been struggling with my weight, and want to know if there's something wrong with me. I've gone through both the extremes of weight loss followed by weight gain in past two years. 2 years back I weighed about 102kgs and could no longer bear living in that condition. Made changes to diet, started exercising, even got a personal trainer during the later stages to improve my workout. From 102 kgs in May 2023, i dropped to around 79 kgs in April 2024. I was pushing ahead strongly, but ended up injuring my knee in May 2024. I had to take a break for about 2 months before getting back. But the rhythm broke so bad, i ended up not going to the gym for more than a year. I started exercising back in September 2025, beginning another phase of loosing weight and gaining muscle. The problem is that I gained too much weight, without being too careless about my diet. Although I didn't entirely follow a lean diet, I also didn't go on a rampage eating everything i can lay down my hands on. I maintained an overall steady protein diet ensuring i eat too much junk. But still I managed to end up at about 97kg weight in August 2025. My wife and friends have been telling me that there's something wrong with me, which is causing this huge fluctuation of about 42 kgs in 2 years. Can someone please tell me if there's something I need to check/test to find if there's something wrong with me.

Tldr - Weight fluctuated 42 kgs in 2 years, I want to find out if there's something wrong with me. I want to know if there are any tests to find out the same.