metadata: total_results seems inconsistent

[MCOfficer]

i am trying to get the total number of posts in my subreddit. for context, all posts in this sub are from the same user (a bot account).

the following query returns 4570 as total_results

https://api.pushshift.io/reddit/search/submission/?subreddit=spacewallsdump&metadata=true&size=0

, however, once i add the author field to the query, i get 4658:

https://api.pushshift.io/reddit/search/submission/?subreddit=spacewallsdump&metadata=true&size=0&author=scifiwalls-bot

and when i change size to 1, i get 4694:

https://api.pushshift.io/reddit/search/submission/?subreddit=spacewallsdump&metadata=true&size=1&author=scifiwalls-bot

Note that these values can be slightly off, since the bot could be submitting new posts while i am testing. however, the first two queries were tested with just a few seconds delay, and the bot doesn't submit faster than 1 post a second. a discrepancy of 100 posts in such a short time doesn't seem reasonable to me.