I didnt say anything about kettlebells being better.
The OP asked if training will kettlebells in the short run (months) will make him lose gains and most responses implied yes barbells are necessary, barbells are absolutely better, unilateral movements are inferior etc.
Like I and a minority pointed out, don't overthink it, your muscles don't know the shape of weight that they're moving... use what you have for now and even when you can use barbells again you can mix in some dumbells, kettlebells etc.
If barbells were such an end-all be-all then pro athletes wouldn't use anything but barbells in their workouts. Any deviation to mix in a dumbell woukd be counter-productive as they could he using a barbell instead for even more gains
If your logic is "you can use more weight with a barbell than a dumbell so it must be better" then machines would be even better than barbells lol, obviously weights on an end of a bar have different center of gravity and require less balancing.