This is definitely a problem. Defensive problems do appear, but much more rarely than attacking ones. I guess their rating gets pumped up pretty fast, because they're much harder to solve - or people are just used to looking for winning variation - so they disappear from lower ratings altogether. Aimchess[1] worked surprisingly well for me to get at least a bit more well rounded training going on.

A lot of defence can also fall under the umbrella of strategy rather than tactics, as in the dream scenario you'd basically only be trying to keep the position in a state that has all the needed defences built into it. Doesn't really work like that in reality. But studying and practicing strategic principles of the positions you're playing could be another thing that could help, especially the pitfalls of those positions. Most positions have a bunch of well known pitfalls that will improve your defensive game quick if you keep those in mind while playing. A lot of these can be found on YouTube.

One other thing to try out is to also play normal tactics, but with the board flipped.

[1]: https://aimchess.com