v4.0.0 release is incoming. As mentioned in
v4.0.0 pre-release page, substrate pallet-contracts later than this commit (shows up in polkadot-v0.9.32 branch for the first time) start to support ink!
Are there any backward incompatibility issues with ink! v3.4.0 or lower? which contracts developers need to be aware of. If yes, what exactly are they?