Unfortunately lazyAttrsOf isn't a panacea against strictness. I described this in the docs, namely that it doesn't work 100% with mkIf false-style definitions, which is also apparent from ofborg's error, because it leads to

This is why lazyAttrsOf should only be used where either mkIf style definitions can't be used anyways (which is seldom the case, but an example is the one use introduced in #70138), or by making sure an unset value is somehow later processed/filtered, which is what I'm doing in #75584

ACK. I figured I'd throw it at ofborg and see if it'd stick, since it had been working fine on my local machine so far.