Why does disabling a struct's postblit increase its size in memory?

[Per Nordlöw]

On Saturday, 2 March 2024 at 19:28:08 UTC, Per Nordlöw wrote:
> On Saturday, 2 March 2024 at 19:11:42 UTC, kinke wrote:
>> Not according to run.dlang.io, for all available DMD versions. 
>> Perhaps your tested `S` was nested in some function/aggregate 
>> and so had an implicit context pointer.
>
> Ahh. Yes. Indeed. My mistake. Thanks.

Thanks. Neither my websearches nor ChatGPT plus couldn't figure 
that out.