localPosts/status_count counter sometimes goes backwards

[markrprior]

Steps to reproduce the problem

It's an intermittent problem and I've seen nothing obvious that triggers it but I have noticed that on occasion if I poll a site the nodeinfo localPosts and the (I assume linked) mastodon instance v1 status_count field have recorded a smaller number. The size of the delta is variable, it can be just a couple but then an example from earlier today
airpollution.science: NEGATIVE: new=1294 old=2921 delta=-1627
My script polls sites once a day.

Expected behaviour

I expected the number to only increase (unless the counter wraps)

Actual behaviour

Sometimes the number gets smaller

Detailed description

No response

Specifications

It seems to happen on all versions of mastodon.

[markrprior]

While I can appreciate that this might be caused by people deleting a post the example I posted seemed extreme for that situation. Depending on how it is implemented it could multiple count edits as (+1 post, -1 delete, +1 post) which would also seem wrong to me. I think that ideally the only thing that should increment the counter is creating a post. Deleting or modifying it later shouldn't change the counter.