Because of the notifications, I happened to notice earlier today that my bronze badge count showed 1030, but now it shows 918.
There is a recent announcement about change of logic how the publicity badges (Announcer, Booster, Publicist). are counted: Missing publicist badge? That is the reason why many people received Announcer badges recently. Concerning the removal of some of the badges, notice specifically this part: "We also identified a small number of users who will receive duplicate badges on the initial rollout of the new logic - meaning they were awarded for a question with the old logic, but now are being awarded for an answer - the duplicate badges will be removed over the next few days after the corrected badges are awarded."
This seems to be the most likely explanation. If I understand the quoted part correctly, for each removed badge you should have been awarded a new badge for link to an answer in the recent recalculation. You can check whether the counts seem reasonable using this SEDE query: Publicity badges awarded within a given period. (
However, the new badges will be shown there only after the next update of the database - so you have to wait a day or two or to count manually. The query shows that you were awarded 125 Announcer badges and one Booster badge in the dates near the recalculation. So some of those might be badges for answers - which replaced the badges for questions which were taken away. Of course, the same query can be used also for any other date range.)
The linked post contains also further details on the recent change. I will add a link also to a related posts on Mathematics Meta: Change in computation of “Announcer” badges? (Although that one does not discuss the possible removal of badges.)
Of course, the count is not important in any meaningful way, and I hardly notice it usually. But I don't usually expect it to go down.
Indeed, under normal circumstances, the only type of badges that are taken away are tag-badges. (If you no longer fulfill the criteria.) Other situations when a badge is removed seem to be rather exceptional and very likely rare. See: Is it possible to lose badges? and the section "What can cause a badge to be lost/revoked/taken away after it is awarded?" of the FAQ post How do “badges” work? (On Mathematics Meta: Can badges be unearned? and Can an awarded tag-badge be withdrawn?)