It looks like the constructor is being hit (and used for the first element), but (afterwards) the default values (and the values inside the constructor) aren’t being used. For unexposed values, copying the value of the previous element doesn’t seem to cause a big problem (provided you don’t really need the default value, of course). But for exposed values, it seems to permanently link them. A workaround is to always leave the last element blank. Blanks (nulls) seem to be unexposed.
I’m in 2021.3.22f1 and 2022.3.3f1 since it seems people didn’t have that problem with lists of exposed references before.
Yeah, I’ll eventually make a bug report, but this is easier (and someone may be bumping against this now).