[bearburger]

I feel your pain. Yesterday client's "wp developer" asked me to downgrade from 7.2 to 5.6 because "7.x is not stable enough".

[h1d]

You should know it means his understanding on 7.x is not stable enough.

[DanHulton]

Or that they use a bunch of deprecated or modified functions, and haven't cleaned them up yet - so their code isn't stable on 7.x.