Yes really. I'm far from being an elite bodybuilder but I lift (somewhat) heavy s
hit. I also know how to do home bodyweight (or improvised weight) exercises. Like I said, I've done it for previous lockdowns. And I always noted a loss of strength. Not huge but some.
I don't see how you can maintain the same level of power if you're not lifting the same weights. I lift about 140kg on a deadlift. If I don't have a bar and weights at home, and least of all 140kg to lift in proper deadlift form, I'm not gonna maintain that strength. It's gonna drop. Same for squats. Somewhat easier to do but I don't have the weight. Etc etc.
But yeah, bands help, I have and use them...