I reverted back to 2.42.1, and the problem still occurs when building the latest network-manager.
I also tried building our bluez snap with 2.43, and it appears normal (ie. it didn't increase in size). Next I built our previous release of the network-manager snap (1.2.2-15), and it also builds normally, so I think this problem is related to the changes made to the network-manager snap post 1.2.2-15.
As stated before, we need to find the root cause before we submit a fix. Your description doesn't mention what version of snapcraft you used.
I checked the changelog for snapcraft 2.43, which was released recently and couldn't find any changes that might've caused this problem:
https:/ /github. com/snapcore/ snapcraft/ releases/ tag/2.43
I reverted back to 2.42.1, and the problem still occurs when building the latest network-manager.
I also tried building our bluez snap with 2.43, and it appears normal (ie. it didn't increase in size). Next I built our previous release of the network-manager snap (1.2.2-15), and it also builds normally, so I think this problem is related to the changes made to the network-manager snap post 1.2.2-15.